The Hooghly River or the Bhāgirathi-Hooghly, called ‘Ganga’ traditionally, is an approximately 260 kilometres (160 mi) long distributary of the Ganges River in West Bengal, India. It splits from the Ganges as a canal in Murshidabad District at the Farakka Barrage. The town of Hugli-Chinsura, formerly Hooghly, is located on the river, in the Hooghly (district). The origins of the Hooghly name are uncertain, whether the city or the river was named first.
The Farakka Barrage is a dam that diverts water from the Ganges into a canal near the town of Tildanga in Malda district. This supplies the Hooghly with adequate water even in the dry season. It parallels the Ganges, past Dhulian, until just above Jahangirpur where the canal ends and the river takes its own course. Just south of Jahangirpur it leaves the Ganges area and flows south past Jiaganj Azimganj, Murshidabad, and Baharampur. South of Baharampur and north of Palashi it used to form the border between Bardhaman District and Nadia District, but while the border has remained the same the river is now often east or west of its former bed. The river then flows south past Katwa, Navadwip and Kalna. At Kalna it originally formed the border between Nadia District and Hooghly District, and then further south between Hooghly District and North 24 Parganas District. It flows past Halisahar, Chunchura, Konnagar, and Kamarhati. Then just before entering the twin cities of Kolkata (Calcutta) and Howrah, it turns to the southwest. At Nurpur it enters an old channel of the Ganges and turns south to empty into the Bay of Bengal. Two of its well known tributaries are Damodar and Rupnarayan.
Harvest fields of Bengal
The scenery along the banks of the Hooghly varies considerably. From the sea nothing but sandbanks and mud formations covered with coarse herbage at first greet the eye, then as the river narrows, cultivated rice fields and sleepy hamlets reposing within the foliage of beautiful groves, render the view at once pleasing and picturesque.
Note : The above story is based on materials provided by Wikipedia.
The Colima volcano, also known as the ‘Fire Volcano,’ has erupted, shooting columns of ash and smoke nearly 5,000 feet into the air over western Mexico. (Jan. 13)
With support from the NASA Astrobiology Program, Cavosie brought students from the University of Puerto Rico to study outcrops at the Rock Elm meteorite impact structure. Reidite was found in the samples they collected. Credit: Aaron Cavosie
Scientists have discovered one of the rarest minerals on Earth in a Wisconsin impact crater.
Aaron Cavosie of the University of Puerto Rico, and member of the NASA Astrobiology Institute Team at the University of Wisconsin, brought students to an impact site in Rock Elm, Wisconsin to collect samples. In those samples, Cavosie and colleagues discovered the mineral reidite, making Rock Elm the fourth site on Earth where the mineral has been found in nature.
Reidite is created at high pressures and was first identified in the laboratory in the 1960s. The conditions in which reidite forms have been well-constrained by experiments in the lab but, prior to Rock Elm, it was only found naturally in the Chesapeake Bay Impact Structure (Virginia), the Ries Crater (Germany), and the Xiuyan Crater (China).
The Rock Elm structure is 6.5 kilometers in diameter and was formed during the Middle Ordovician. This means that the reidite found at Rock Elm is at least 450 million years old, making it the oldest preserved reidite yet discovered.
Another important aspect of the research is that the reidite was found in sandstone – the first time the mineral was spotted in this type of rock. There are many other impact structures that have been formed in sandstone, and its possible that a re-examination of these sites could reveal more reidite.
“I get the sense that, because reidite had never been found in this kind of rock, if something’s never found there, your not going to go look for it purposefully,” said Cavosie in an interview with Wisconsin Public Radio. “Now that we’ve identified this recorder of even far more extreme impact conditions than what was known previously at Rock Elm, that tool can be applied to many, many other localities to try to recreate the impact conditions and better understand the effects on the surface environments of some of these impacts.”
Wisconsin Public Radio produced an interview with Aaron Cavosie and Bill Cordua of UW-River Falls, who discovered the Rock Elm disturbance. To listen to the show, visit: http://www.wpr.org/listen/682916
The initial findings were presented at the 2014 GSA Annual Meeting in Vancouver.
Video
Note : The above story is based on materials provided by Astrobio.net This story is republished courtesy of NASA’s Astrobiology Magazine. Explore the Earth and beyond at www.astrobio.net .
This is a visual representation of the evolution of the European continental ecosystems across the Cretaceous-Paleogene Boundary Extinction Event: the diverse vertebrate assemblages of the latest Cretaceous, with dinosaurs, crocodiles, turtles and mammals (bottom image; see ZooKeys review of Csiki-Sava et al., doi: 10.3897/zookeys.469.8439 for the identity of the different taxa represented), were wiped almost completely, with only a few groups (here epitomized by certain mammals and turtles) surviving into the Paleogene (top image). The backgrounds show more or less accurate reconstructions of the European paleogeography during the latest Cretaceous (bottom; K), respectively the Paleogene (top; Pg). Credit: Background paleogeography reconstructions – Dr. Ron Blakey, Professor Emeritus Northern Arizona University; fossils: Dr. Jeremy E. Martin / CC-BY 4.0
Dinosaurs flourished in Europe right up until the asteroid impact that wiped them out 66 million years ago, a new study shows.
The theory that an asteroid rapidly killed off the dinosaurs is widely recognized, but until recently dinosaur fossils from the latest Cretaceous–the final stanza of dinosaur evolution–were known almost exclusively from North America. This has raised questions about whether the sudden decline of dinosaurs in the American and Canadian west was merely a local story.
The new study synthesizes a flurry of research on European dinosaurs over the past two decades. Fossils of latest Cretaceous dinosaurs are now commonly discovered in Spain, France, Romania, and other countries.
By looking at the variety and ages of these fossils, a team of researchers led by Zoltán Csiki-Sava of the University of Bucharest’s Faculty of Geology and Geophysics has determined that dinosaurs remained diverse in European ecosystems very late into the Cretaceous.
In the Pyrenees of Spain and France, the best area in Europe for finding latest Cretaceous dinosaurs, meat and plant-eating species are present and seemingly flourishing during the final few hundred thousand years before the asteroid hit.
Dr Csiki-Sava said “For a long time, Europe was overshadowed by other continents when the understanding of the nature, composition and evolution of latest Cretaceous continental ecosystems was concerned. The last 25 years witnessed a huge effort across all Europe to improve our knowledge, and now we are on the brink of fathoming the significance of these new discoveries, and of the strange and new story they tell about life at the end of the Dinosaur Era.”
Dr Steve Brusatte of the University of Edinburgh’s School of GeoSciences (UK), an author on the report, added: “Everyone knows that an asteroid hit 66 million years ago and dinosaurs disappeared, but this story is mostly based on fossils from one part of the world, North America. We now know that European dinosaurs were thriving up to the asteroid impact, just like in North America. This is strong evidence that the asteroid really did kill off dinosaurs in their prime, all over the world at once.”
The new study is published in the open access journal ZooKeys. It reviews the fossil record of Late Cretaceous land-living vertebrates (including dinosaurs) from Europe and provides the most up-to-date survey of how these animals were changing in the run up to the asteroid impact.
Reference:
Zoltan Csiki-Sava, Eric Buffetaut, Attila Ősi, Xabier Pereda-Suberbiola, Stephen L. Brusatte. Island life in the Cretaceous – faunal composition, biogeography, evolution, and extinction of land-living vertebrates on the Late Cretaceous European archipelago. ZooKeys, 2015; 469: 1 DOI: 10.3897/zookeys.469.8439
Note : The above story is based on materials provided by Pensoft Publishers. The original story is licensed under a Creative Commons License.
A global “gold rush” has led to a significant increase of deforestation in the tropical forests of South America.
This is according to new research publish today, 14 January, in IOP Publishing’s journal Environmental Research Letters, which has highlighted the growing environmental impact of gold mining in some of the most biologically diverse regions in the tropics.
Researchers from the University of Puerto Rico have shown that between 2001 and 2013, around 1680 km2 of tropical forest was lost in South America as a result of gold mining, which increased from around 377 km2 to 1303km2 since the global economic crisis in 2007.
Furthermore, around 90 per cent of this forest loss occurred in just four areas and a large proportion occurred within the vicinity of conservation areas.
Lead author of the research Nora L. Álvarez-Berríos said: “Although the loss of forest due to mining is smaller in extent compared to deforestation caused by other land uses, such as agriculture or grazing areas, deforestation due to mining is occurring in some of the most biologically diverse regions in the tropics. For example, in the Madre de Dios Region in Perú, one hectare of forest can hold up to 300 species of trees.”
Driven by personal consumption and uncertainty in global financial markets, global gold production has increased to meet rising demand, increasing from around 2445 metric tons in 2000 to around 2770 metric tons in 2013.
Increased demand for gold has been paralleled by a dramatic increase in price — the price of gold increased from $250/ounce in 2000 to $1300/ounce in 2013.
This has stimulated new gold mining activities around the world and made it feasible to mine for gold in areas that were not previously profitable for mining, such as deposits underneath tropical forests.
This can lead to extensive forest loss and result in serious environmental and ecological impacts, caused by the removal of vegetation, the set-up of roads and railways for access and the creation of unorganised settlements.
Some of the long-term impacts include the failure of vegetation to regrow, changing of rainfall patterns, the permanent loss of biodiversity, and a release of CO2 into the atmosphere.
In their study, the researchers sought to quantify the impacts of gold mines in tropical forests by creating a geographical database that highlighted the location of newly developed mines between 2000 and 2013.
The database was then cross-referenced with annual land cover maps showing the change of forest cover over the same period.
The study encompassed the tropical and subtropical forest biome in South America below 1000 m, covering Colombia, Venezuela, Guyana, Suriname, French Guiana, Brazil, Ecuador, Peru, and Bolivia.
Results showed that over the 13 year period, 89 per cent of forest loss occurred in just four regions: the Guianan moist forest ecoregion; the Southwest Amazon moist forest ecoregion; the Tapajós-Xingú moist forest ecoregion; and The Magdalena Valley-Urabá region.
Although there was little deforestation inside strict protection areas, around a third of the total deforestation occurred within a 10-km buffer zone around these areas and thus made the areas susceptible to harmful impacts from chemical pollutants that are dispersed from a mining area.
“To decrease the amount of deforestation that is occurring as a result of gold mining in the tropical forests, it is important that awareness is raised among gold consumers to understand the environmental and social impacts of buying gold jewellery or investing in gold.
“It is important to also encourage more responsible ways of extracting gold by helping miners to extract in a more efficient way to reduce deeper encroachment into the forests,” continued Álvarez-Berríos.
Reference:
Nora L Alvarez-Berríos, T Mitchell Aide. Global demand for gold is another threat for tropical forests. Environmental Research Letters, 2015; 10 (1): 014006 DOI: 10.1088/1748-9326/10/1/014006
A new species of marine reptile from the Jurassic era has been identified from fossils found on the Isle of Skye.
The dolphin-like creatures were as long as 14 feet from snout to tail, and inhabited warm, shallow seas around Scotland some 170 million years ago, researchers say.
They were near the top of the food chain at the time and preyed on fish and other reptiles.
A team of palaeontologists – led by the University and including many Scottish institutions – studied fossil fragments of skulls, teeth, vertebrae and an upper arm bone unearthed on the island over the past 50 years.
They identified several examples of extinct aquatic animals – known as ichthyosaurs – which lived during the Early-to-Middle Jurassic, including the entirely new species.
The team is the largest collaborative group of palaeontologists working in Scotland.
Their analysis of the fossil collection is the first study of ichthyosaurs found in Scotland, and many of the specimens studied have been donated to museums by amateur collectors.
Donated fossils
“During the time of dinosaurs, the waters of Scotland were prowled by big reptiles the size of motor boats. Their fossils are very rare, and only now, for the first time we’ve found a new species that was uniquely Scottish,” says Dr Steve Brusatte of the School of GeoSciences. “Without the generosity of the collector who donated the bones to a museum instead of keeping them or selling them, we would have never known that this amazing animal existed.”
The new species – Dearcmhara shawcrossi – is named in honour of an amateur enthusiast, Brian Shawcross, who recovered the creature’s fossils from the island’s Bearreraig Bay in 1959.
Dearcmhara – pronounced ‘jark vara’ – is Scottish Gaelic for marine lizard, and pays homage to the history of Skye and the Hebrides.
The species is one of the few to have ever been given a Gaelic name.
Landmass shift
During the Jurassic Period, much of Skye was under water.
At the time, it was joined to the rest of the UK and was part of a large island positioned between landmasses that gradually drifted apart and became Europe and North America.
Skye is one of the few places in the world where fossils from the Middle Jurassic Period can be found.
The team say discoveries made there could provide valuable insights into how marine reptiles evolved.
The study is published in the Scottish Journal of Geology.
“During the time of dinosaurs, the waters of Scotland were prowled by big reptiles the size of motor boats. Their fossils are very rare, and only now, for the first time we’ve found a new species that was uniquely Scottish,” says Dr Brusatte.
“Not only is this a very special discovery, but it also marks the beginning of a major new collaboration involving some of the most eminent palaeontologists in Scotland … We are excited by the programme of work and are already working on additional new finds. This is a rich heritage for Scotland,” adds Dr Nick Fraser National Museums Scotland.
Reference:
“Ichthyosaurs from the Jurassic of Skye, Scotland.” Scottish Journal of Geology, first published on January 11, 2015, DOI: 10.1144/sjg2014-018
This is a map of the Ganges (yellow), Brahmaputra (violet), and Meghna (green) drainage basins. Created with ArcExplorer and Adobe Illustrator, based on Natural Earth data.
The Ganges, also Ganga is a trans-boundary river of Asia which flows through India and Bangladesh. The 2,525 km (1,569 mi) river rises in the western Himalayas in the Indian state of Uttarakhand, and flows south and east through the Gangetic Plain of North India into Bangladesh, where it empties into the Bay of Bengal. It is the third largest river by discharge.
The Ganges is the most sacred river to Hindus. It is also a lifeline to millions of Indians who live along its course and depend on it for their daily needs. It is worshipped as the goddess Ganga in Hinduism. It has also been important historically, with many former provincial or imperial capitals (such as Pataliputra, Kannauj, Kara, Kashi, Allahabad, Murshidabad, Munger, Baharampur, Kampilya, and Kolkata) located on its banks.
The Ganges was ranked as the fifth most polluted river of the world in 2007. Pollution threatens not only humans, but also more than 140 fish species, 90 amphibian species and the endangered Ganges river dolphin. The Ganga Action Plan, an environmental initiative to clean up the river, has been a major failure thus far, due to corruption, lack of technical expertise, poor environmental planning, and lack of support from religious authorities.
The Ganges begins at the confluence of the Bhagirathi and Alaknanda rivers at Devprayag. The Bhagirathi is considered to be the true source in Hindu culture and mythology, although the Alaknanda is longer The headwaters of the Alakananda are formed by snowmelt from such peaks as Nanda Devi, Trisul, and Kamet. The Bhagirathi rises at the foot of Gangotri Glacier, at Gaumukh, at an elevation of 3,892 m (12,769 ft).
The Himalayan headwaters of the Ganges river in the Garhwal region of Uttarakhand, India. The headstreams and rivers are labeled in italics; the heights of the mountains, lakes, and towns are displayed in parentheses in metres.
Although many small streams comprise the headwaters of the Ganges, the six longest and their five confluences are considered sacred. The six headstreams are the Alaknanda, Dhauliganga, Nandakini, Pindar, Mandakini, and Bhagirathi rivers. The five confluences, known as the Panch Prayag, are all along the Alaknanda. They are, in downstream order: Vishnuprayag, where the Dhauliganga joins the Alaknanda; Nandprayag, where the Nandakini joins; Karnaprayag, where the Pindar joins; Rudraprayag, where the Mandakini joins; and, finally, Devprayag, where the Bhagirathi joins the Alaknanda to form the Ganges River proper.
After flowing 250 kilometres (160 mi) through its narrow Himalayan valley, the Ganges emerges from the mountains at Rishikesh, then debouches onto the Gangetic Plain at the pilgrimage town of Haridwar. At Haridwar, a dam diverts some of its waters into the Ganges Canal, which irrigates the Doab region of Uttar Pradesh, whereas the river, whose course has been roughly southwest until this point, now begins to flow southeast through the plains of northern India.
The Ganges follows an 800-kilometre (500 mi) arching course passing through the cities of Kannauj, Farukhabad, and Kanpur. Along the way it is joined by the Ramganga, which contributes an average annual flow of about 500 m3/s (18,000 cu ft/s). The Ganges joins the Yamuna at the Triveni Sangam at Allahabad, a holy confluence in Hinduism. At their confluence the Yamuna is larger than the Ganges, contributing about 2,950 m3/s (104,000 cu ft/s), or about 58.5% of the combined flow.
Now flowing east, the river meets the Tamsa River (also called Tons), which flows north from the Kaimur Range and contributes an average flow of about 190 m3/s (6,700 cu ft/s). After the Tamsa the Gomti River joins, flowing south from the Himalayas. The Gomti contributes an average annual flow of about 234 m3/s (8,300 cu ft/s). Then the Ghaghara River(Karnali River), also flowing south from the Himalayas of Nepal, joins. The Ghaghara(Karnali), with its average annual flow of about 2,990 m3/s (106,000 cu ft/s), is the largest tributary of the Ganges. After the Ghaghara(Karnali) confluence the Ganges is joined from the south by the Son River, contributing about 1,000 m3/s (35,000 cu ft/s). The Gandaki River, then the Kosi River, join from the north flowing from Nepal, contributing about 1,654 m3/s (58,400 cu ft/s) and 2,166 m3/s (76,500 cu ft/s), respectively. The Kosi is the third largest tributary of the Ganges, after the Ghaghara(Karnali) and Yamuna.
Along the way between Allahabad and Malda, West Bengal, the Ganges passes the towns of Chunar, Mirzapur, Varanasi, Ghazipur, Patna, Bhagalpur, Ballia, Buxar, Simaria, Sultanganj, and Saidpur. At Bhagalpur, the river begins to flow south-southeast and at Pakur, it begins its attrition with the branching away of its first distributary, the Bhāgirathi-Hooghly, which goes on to become the Hooghly River. Just before the border with Bangladesh the Farakka Barrage controls the flow of the Ganges, diverting some of the water into a feeder canal linked to the Hooghly for the purpose of keeping it relatively silt-free. The Hooghly River is formed by the confluence of the Bhagirathi River and Jalangi River at Nabadwip, and Hooghly has a number of tributaries of its own. The largest is the Damodar River, which is 541 km (336 mi) long, with a drainage basin of 25,820 km2 (9,970 sq mi). The Hooghly River empties into the Bay of Bengal near Sagar Island. Between Malda and the Bay of Bengal, the Hooghly river passes the towns and cities of Murshidabad, Nabadwip, Kolkata and Howrah.
After entering Bangladesh, the main branch of the Ganges is known as the Padma. The Padma is joined by the Jamuna River, the largest distributary of the Brahmaputra. Further downstream, the Padma joins the Meghna River, the second largest distributary of the Brahmaputra, and takes on the Meghna’s name as it enters the Meghna Estuary, which empties into the Bay of Bengal.
The Ganges Delta, formed mainly by the large, sediment-laden flows of the Ganges and Brahmaputra rivers, is the world’s largest delta, at about 59,000 km2 (23,000 sq mi). It stretches 322 km (200 mi) along the Bay of Bengal.
Only the Amazon and Congo rivers have a greater average discharge than the combined flow of the Ganges, the Brahmaputra, and the Surma-Meghna river system. In full flood only the Amazon is larger
Geology
The Indian subcontinent lies atop the Indian tectonic plate, a minor plate within the Indo-Australian Plate. Its defining geological processes commenced seventy-five million years ago, when, as a part of the southern supercontinent Gondwana, it began a northeastwards drift—lasting fifty million years—across the then unformed Indian Ocean. The subcontinent’s subsequent collision with the Eurasian Plate and subduction under it, gave rise to the Himalayas, the planet’s highest mountains. In the former seabed immediately south of the emerging Himalayas, plate movement created a vast trough, which, having gradually been filled with sediment borne by the Indus and its tributaries and the Ganges and its tributaries, now forms the Indo-Gangetic Plain.
The Indo-Gangetic Plain is geologically known as a foredeep or foreland basin.
Hydrology
The hydrology of the Ganges River is very complicated, especially in the Ganges Delta region. One result is different ways to determine the river’s length, its discharge, and the size of its drainage basin.
The name Ganges is used for the river between the confluence of the Bhagirathi and Alaknanda rivers, in the Himalayas, and the India-Bangladesh border, near the Farakka Barrage and the first bifurcation of the river. The length of the Ganges is frequently said to be slightly over 2,500 km (1,600 mi) long, about 2,505 km (1,557 mi), to 2,525 km (1,569 mi), or perhaps 2,550 km (1,580 mi). In these cases the river’s source is usually assumed to be the source of the Bhagirathi River, Gangotri Glacier at Gomukh, and its mouth being the mouth of the Meghna River on the Bay of Bengal. Sometimes the source of the Ganges is considered to be at Haridwar, where its Himalayan headwater streams debouch onto the Gangetic Plain.
In some cases, the length of the Ganges is given for its Hooghly River distributary, which is longer than its main outlet via the Meghna River, resulting in a total length of about 2,620 km (1,630 mi), from the source of the Bhagirathi, or 2,135 km (1,327 mi), from Haridwar to the Hooghly’s mouth. In other cases the length is said to be about 2,240 km (1,390 mi), from the source of the Bhagirathi to the Bangladesh border, where its name changes to Padma.
A 1908 map showing the course of the Ganges and its tributaries. Major left-bank tributaries include Gomti (Gumti), Ghaghara (Gogra), Gandaki (Gandak), and Kosi (Kusi); major right-bank tributaries include Yamuna (Jumna), Son, Punpun and Damodar.
The Tons-Yamuna-Ganga continuous flow is the longest river in the Ganges basin. However, by convention, Tons is considered as a separate river, and the length of Ganga and Yamuna is calculated from Gangotri and Yamunotri respectively. If calculated from source of Tons, the length of Tons-Yamuna-Ganga river is 2,758 km.
For similar reasons, sources differ over the size of the river’s drainage basin. The basin covers parts of four countries, India, Nepal, China, and Bangladesh; eleven Indian states, Himachal Pradesh, Uttarakhand, Uttar Pradesh, Madhya Pradesh, Chhattisgarh, Bihar, Jharkhand, Punjab, Haryana, Rajasthan, West Bengal, and the Union Territory of Delhi. The Ganges basin, including the delta but not the Brahmaputra or Meghna basins, is about 1,080,000 km2 (420,000 sq mi), of which 861,000 km2 (332,000 sq mi) are in India (about 80%), 140,000 km2 (54,000 sq mi) in Nepal (13%), 46,000 km2 (18,000 sq mi) in Bangladesh (4%), and 33,000 km2 (13,000 sq mi) in China (3%). Sometimes the Ganges and Brahmaputra–Meghna drainage basins are combined for a total of about 1,600,000 km2 (620,000 sq mi), or 1,621,000 km2 (626,000 sq mi). The combined Ganges-Brahmaputra-Meghna basin (abbreviated GBM or GMB) drainage basin is spread across Bangladesh, Bhutan, India, Nepal, and China.
The Ganges basin ranges from the Himalaya and the Transhimalaya in the north, to the northern slopes of the Vindhya range in the south, from the eastern slopes of the Aravalli in the west to the Chota Nagpur plateau and the Sunderbans delta in the east. A significant portion of the discharge from the Ganges comes from the Himalayan mountain system. Within the Himalaya, the Ganges basin spreads almost 1,200 km from the Yamuna-Satluj divide along the Simla ridge forming the boundary with the Indus basin in the west to the Singalila Ridge along the Nepal-Sikkim border forming the boundary with the Brahmaputra basin in the east. This section of the Himalaya contains 9 of the 14 highest peaks in the world over 8,000m in height, including Mount Everest which is the high point of the Ganges basin. The other peaks over 8,000m in the basin are Kangchenjunga, Lhotse, Makalu, Cho Oyu, Dhaulagiri, Manaslu, Annapurna and Shishapangma. The Himalayan portion of the basin includes the south-eastern portion of the state of Himachal Pradesh, the entire state of Uttarakhand, the entire country of Nepal and the extreme north-western portion of the state of West Bengal.
The discharge of the Ganges also differs by source. Frequently, discharge is described for the mouth of the Meghna River, thus combining the Ganges with the Brahmaputra and Meghna. This results in a total average annual discharge of about 38,000 m3/s (1,300,000 cu ft/s), or 42,470 m3/s (1,500,000 cu ft/s). In other cases the average annual discharges of the Ganges, Brahmaputra, and Meghna are given separately, at about 16,650 m3/s (588,000 cu ft/s) for the Ganges, about 19,820 m3/s (700,000 cu ft/s) for the Brahmaputra, and about 5,100 m3/s (180,000 cu ft/s) for the Meghna.
The maximum peak discharge of the Ganges, as recorded at Hardinge Bridge in Bangladesh, exceeded 70,000 m3/s (2,500,000 cu ft/s). The minimum recorded at the same place was about 180 m3/s (6,400 cu ft/s), in 1997.
The hydrologic cycle in the Ganges basin is governed by the Southwest Monsoon. About 84% of the total rainfall occurs in the monsoon from June to September. Consequently, streamflow in the Ganges is highly seasonal. The average dry season to monsoon discharge ratio is about 1:6, as measured at Hardinge Bridge. This strong seasonal variation underlies many problems of land and water resource development in the region. The seasonality of flow is so acute it can cause both drought and floods. Bangladesh, in particular, frequently experiences drought during the dry season and regularly suffers extreme floods during the monsoon.
In the Ganges Delta many large rivers come together, both merging and bifurcating in a complicated network of channels. The two largest rivers, the Ganges and Brahmaputra, both split into distributary channels, the largest of which merge with other large rivers before themselves joining. This current channel pattern was not always the case. Over time the rivers in Ganges Delta have changed course, sometimes altering the network of channels in significant ways.
Before the late 12th century the Bhagirathi-Hooghly distributary was the main channel of the Ganges and the Padma was only a minor spill-channel. The main flow of the river reached the sea not via the modern Hooghly River but rather by the Adi Ganga. Between the 12th and 16th centuries the Bhagirathi-Hooghly and Padma channels were more or less equally significant. After the 16th century the Padma grew to become the main channel of the Ganges. It is thought that the Bhagirathi-Hooghly became increasingly choked with silt, causing the main flow of the Ganges to shift to the southeast and the Padma River. By the end of the 18th century the Padma had become the main distributary of the Ganges. One result of this shift to the Padma was that the Ganges joined the Meghna and Brahmaputra rivers before emptying into the Bay of Bengal, together instead of separately. The present confluence of the Ganges and Meghna formed about 150 years ago.
Near the end of the 18th century, the course of the lower Brahmaputra changed dramatically, altering its relationship with the Ganges. In 1787 there was a great flood on the Teesta River, which at the time was a tributary of the Ganges-Padma River. The flood of 1787 caused the Teesta to undergo a sudden change course (an avulsion), shifting east to join the Brahmaputra and causing the Brahmaputra to shift its course south, cutting a new channel. This new main channel of the Brahmaputra is called the Jamuna River. It flows south to join the Ganges-Padma. Since ancient times the main flow of the Brahmaputra was more easterly, passing by the city of Mymensingh and joining the Meghna River. Today this channel is a small distributary but retains the name Brahmaputra, sometimes Old Brahmaputra. The site of the old Brahmaputra-Meghna confluence, in the locality of Langalbandh, is still considered sacred by Hindus. Near the confluence is a major early historic site called Wari-Bateshwar.
Note : The above story is based on materials provided by Wikipedia.
A beach outcrop at Davis Head on Lopez Island in Washington State, where researchers at Yale discovered veins of aragonite containing oddly light carbon isotopes suggestive of life’s imprint. Credit: Stoddard et al
Life teems all over our planet’s exterior and even down into the lightless oceanic depths. But just how far underground might life be able to hack it?
New research offers evidence of bacteria living as deep as 12 miles underground—quite possibly the deepest life has ever glimpsed. Learning biology’s terrestrial limits, though important in its own right, is critical to understanding life’s rise on other planets with far less forgiving climates and surface conditions than the Earth’s.
“Most studies report microbial life in the crust to no deeper than a few kilometers—just a mile or so,” said Philippa Stoddard, an undergraduate in Yale University’s geology and geophysics department. “Assuming our data are correct, this greatly expands our understanding of the extent of the Earth’s biosphere.”
Stoddard presented the research at the Geological Society of America’s annual meeting in Vancouver, British Columbia on October 21.
Acting on clues from nearly two-decades-old field work, Stoddard and her Yale colleagues examined rocks on Lopez Island in northwestern Washington. An outcrop there containing veins of the mineral aragonite, dredged up to the surface scores of millions of years ago by geological processes, was found to contain weirdly high levels of a lightweight version of the element carbon. This carbon signature is usually produced by microbes that excrete the carbon containing compound methane.
The likeliest explanation is that life forms, once buried deep in the Earth’s crust, altered the ancient aragonite’s carbon signature. These microbes were so far underground they would have had to withstand extreme temperatures and pressures—a dramatic demonstration of life’s robustness that bodes well an ability to take hold in unearthly environments.
“I think that results like ours are very encouraging for the possibility of life on other planets,” said Stoddard. “The more we learn about extreme environments on our own planet, the more we realize how resilient life is.”
The startling discovery initially cropped up in the 1990s. Fieldwork by J.G. Feehan for his 1997 doctoral dissertation with Yale professor Mark T. Brandon, who now is Stoddard’s academic advisor, had identified the aragonite’s very light carbon signatures.
Feehan suggested at the time that the signatures were the fingerprint of super-deep life. His focus, however, was on the geophysics of the rocks hosting the aragonite veins. So the subterranean life hypothesis sat, un-pursued, ever since.
Stoddard and Brandon, along with Yale professor Danny Rye, decided to pick up the thread. They recently returned to the scene in Washington State.
“Professor Brandon and I went back to the outcrop on Lopez Island where Feehan had done his isotopic measurements to see if we could corroborate his data and explore the suggestion of deep life more thoroughly,” explained Stoddard.
Telltale abundances
Specifically, as Feehan had done, Stoddard looked at the ratios of two carbon isotopes, or versions of an element containing different numbers of neutrons. The isotopes in question are carbon-12 and carbon-13, or C-12 and C-13. The former makes up the vast majority of carbon on the Earth. It has six protons and six neutrons in its atomic nucleus. C-13 has an extra, seventh neutron.
Life alters the typical ratio of C-12 to C-13 because most biochemical processes —eating, growth, and so on—divide isotopes into lighter and heavier camps. The way this works is actually pretty simple. Lower-numbered isotopes, possessing less mass, are lighter than higher-numbered isotopes. Lighter objects, like an empty cardboard box, are of course easier to move than a loaded safe of the same size. Similarly, lighter isotopes have an easier time getting about in the push-and-pull of biological matter at Lilliputian scales, driven by energy and molecular interactions.
“Because carbon-12 is the lighter isotope, it is more thermodynamically mobile than carbon-13,” said Stoddard. “It can actually move faster.”
Methane, a common waste product of microbes, contains a single carbon atom plus four hydrogen atoms. When microbes consume carbon-rich molecules and excrete methane, the waste methane containing the lighter, faster isotope C-12 returns to the environment more readily than C-13-laden methane. The typical ratio of one carbon isotope to the other ends up skewed as a result in rocks, for example, as in the case of the Lopez Island aragonite.
“The methane produced by microbes has much less of the heavy isotope than the standard ratio,” said Stoddard.
Some non-biological processes can segregate carbon isotopes as well, but they tend not to do as efficiently, noted Stoddard.
The land down under
The San Juan Islands—including Lopez Island, site of the intriguing aragonite—only became islands as such about 100 million years ago, back in the dinosaurs’ heyday. Before then, these sea bottom rocks, located near what is now Vancouver Island, had subducted under a neighboring chunk of rock, a geological process that often happens where tectonic plates meet at ocean and continental boundaries.
Buried in the bowels of the Earth, pressures and heat metamorphosed the dark basalt rock, creating thin, whitish veins of aragonite. Over time, microbes on the scene then slowly altered the carbon signatures in this aragonite through the methodical excretion of methane gas in this pitch-black, hot, squeezed environment.
Subsurface water trapped with the microbes could have further enabled their subsistence in such a place. The temperatures would likely have exceed 250 degrees Fahrenheit—the known cutoff for even the hardiest of life to still function (in hot springs).
How would these microbes have survived? Counterintuitively, the exceedingly high pressure in a miles-deep habitat—in the neighborhood of 5,000 times the pressure exerted by the atmosphere at sea level—could have helped. High pressures actually can stabilize biomolecules, such as DNA, offsetting the heat’s destructive effects.
Similar scenarios could still persist today around the globe, meaning Earth’s biosphere might extend many miles below the planet’s surface.
“We’ve seen over the past couple decades of exploration that life can survive in an incredible diversity of ecosystems, even in deep-sea vents and glacial ice,” said Stoddard. “If the deep earth was survivable for specialized microbes 100 million years ago, those same strategies could still work today.”
Subsurface refuges
A similar approach could allow extraterrestrial life to get by under the desolate surfaces of worlds such as Mars.
Despite some of the obvious drawbacks of living deeply, microbes that have evolved to persist in such conditions would have advantages over life attempting to take hold aboveground in hostile environments.
Take Mars again as an example. Its surface gets bombarded with hundreds of times more cosmic radiation than Earth’s surface. Mars lacks a shielding magnetic field, so life developing on its surface would have substantially greater exposure to damaging radiation. Deep under the surface, that risk diminishes, along with other risks posed by, say, scalding or freezing temperatures.
“Underground environments would potentially be favorable locations for extraterrestrial life because they are more shielded from harmful surface conditions like cosmic radiation and insulated from extreme surface temperatures,” said Stoddard. “It’s definitely something we should keep in mind as we explore other planets.”
Stoddard and colleagues intend to further study the long-buried Lopez Island rocks to glean more information about how, and if, life had indeed called them home.
“Although our isotope data is highly suggestive of deep life, there are still lots of things we don’t know about this environment that could impact our conclusions,” said Stoddard. “We’re hoping to be able to construct a pretty detailed portrait of this deep ecosystem in the next couple of months.”
Note : The above story is based on materials provided by Astrobio.net This story is republished courtesy of NASA’s Astrobiology Magazine. Explore the Earth and beyond at www.astrobio.net .
This image shows the following: (A) Whole specimen from sample 154 with shallow pits; (B) Partial specimen from sample 154 with deep pits; (C) Partial specimen from sample 157 displaying pits on multiple growth layers; and (D) Incipient steinkern from sample 162 displaying pits preserved as positive relief on lower half of specimen. Credit: John Warren Huntley
When seeking clues about the future effects of possible climate change, sometimes scientists look to the past. Now, a paleobiologist from the University of Missouri has found indications of a greater risk of parasitic infection due to climate change in ancient mollusk fossils. His study of clams from the Holocene Epoch (that began 11,700 years ago) indicates that current sea level rise may mimic the same conditions that led to an upsurge in parasitic trematodes, or flatworms, he found from that time. He cautions that an outbreak in human infections from a related group of parasitic worms could occur and advises that communities use the information to prepare for possible human health risks.
Trematodes are internal parasites that affect mollusks and other invertebrates inhabiting estuarine environments, which are the coastal bodies of brackish water that connect rivers and the open sea. John Huntley, assistant professor of geological sciences in the College of Arts and Science at MU, studied prehistoric clam shells collected from the Pearl River Delta in China for clues about how the clams were affected by changes caused from global warming and the resulting surge in parasites.
“Because they have soft bodies, trematodes do not leave body fossils,” Huntley said. “However, infected clam shells develop oval-shaped pits where the clam grew around the parasite in order to keep it out; the prevalence of these pits and their makeup provide clues to how the clams adapted to fight trematodes. When compared to documented rises in sea level more than 9,300 years ago, we found that we currently are creating conditions for an increase in trematodes in present-day estuarine environments. This could have harmful implications for both animal and human health, including many of the world’s fisheries.”
Modern-day trematodes will first infest mollusks like clams and snails, which are eaten by shore birds and mammals including humans. Symptoms of infection in humans range from liver and gall bladder inflammation to chest pain, fever, and brain inflammation. The infections can be fatal. At least 56 million people globally suffer from one or more foodborne trematode infections, according to the World Health Organization.
Huntley and his team compared these findings to those from his previous study on clams found in the Adriatic Sea. Using data that includes highly detailed descriptions of climate change and radiocarbon dating Huntley noticed a rising prevalence of pits in the clam shells, indicating a higher prevalence of the parasites during times of sea level rise in both the fossils from China and Italy.
“By comparing the results we have from the Adriatic and our new study in China, we’re able to determine that it perhaps might not be a coincidence, but rather a general phenomenon,” Huntley said. “While predicting the future is a difficult game, we think we can use the correspondence between the parasitic prevalence and past climate change to give us a good road map for the changes we need to make.”
Reference:
John Warren Huntley, Franz T. Fürsich, Matthias Alberti, Manja Hethke, Chunlian Liu. A complete Holocene record of trematode–bivalve infection and implications for the response of parasitism to climate change. Proceedings of the National Academy of Sciences, 2014; 111 (51): 18150 DOI: 10.1073/pnas.1416747111
Rock sponges have a highly characteristic and extremely robust rock-like skeleton, which consists of barbed needles called spicules made of silicon dioxide (i.e., glass), which interlock to form a rigid network. Credit: Professor Gert Wörheide
A study led by researchers at Ludwig-Maximilians-Universitaet (LMU) in Munich throws new light on the evolution of the so-called rock sponges, and reveals that conventional, morphology-based taxonomies do not accurately reflect the true genealogical relationships within the group.
Modern approaches to biological systematics have demonstrated that the evolutionary relationships between organisms can best be teased out by combining morphological analysis of fossil material with molecular genetic investigation of the genomes of living species. “This is a challenging task, particularly when fossil evidence is sparse, as in the case of most families of sponges,” says Professor Gert Wörheide of the Geobio-CenterLMU and LMU’s Department of Earth and Environmental Sciences. “The so-called rock sponges represent an exception to this rule insofar as they provide among the richest fossil record of sponges. With the aid of these fossils and the most comprehensive analysis yet carried out of gene sequences from extant species, an international team led by Wörheide has now reassessed the genealogy of the rock sponges — and show that, in many cases, traditional taxonomy does not correctly depict the evolutionary history of the group as a whole.
Rock sponges belong to the class Demospongiae, which account for the great majority of contemporary species assigned to the phylum Porifera. Demosponges are found in tropical, subtropical and temperate regions of the world’s oceans and occur at all depths from shallow reefs to abyssal depths. More than 300 extant species of rock sponges have been recognized, and classified into 41 genera that are assigned to 13 families. However, by comparison with the range of species represented in the fossil record, with over 300 genera comprising 34 families, the degree of diversity found in the contemporary demosponge fauna is comparatively modest. “The origins of modern rock sponges can be traced back over more than 500 million years into the Paleozoic, and this suggests that much more research will be needed before we understand their evolutionary history,” Wörheide adds.
Rock sponges have a highly characteristic and extremely robust rock-like skeleton, which consists of barbed needles called spicules made of silicon dioxide (i.e., glass), which interlock to form a rigid network. The form and structure of the skeletal elements provide some of the most important characters used to classify the rock sponges. “However, their precise classification and many aspects of their evolutionary history are still the subject of controversial debate,” says Astrid Schuster, a doctoral student in Wörheide’s group, who is first author of the new study. “Previous classifications were largely based on morphological similarities, and these led taxonomists to place many genera in the order ‘Lithistida’, a dubious grouping which is still cited frequently in the literature,” she explains. With the aid of international colleagues, the team has now extended earlier molecular systematic studies and sequenced a specific pair of genes in each of 68 individual species of rock sponge, which had previously been assigned to 21 genera and 12 families. In addition, the team made use of previously reported gene sequences that were available in public databases.
The researchers correlated the molecular genetic results with characteristic features of the skeletal morphology, such as the type and configuration of the siliceous spicules. “The new findings refute some of the assumptions that have been made regarding the course of rock sponge evolution, and demonstrate that some species have been assigned to genera to which they do not actually belong,” says Schuster. Indeed, it is now abundantly clear that ‘Lithistida’ does not constitute a natural group, i.e., not all of its members can be derived from a direct common ancestor. In particular, the new work shows that classifications based on skeletal elements require thorough reassessment, because some of the different types of spicules that are characteristic for rock sponges arose, or were lost, several times independently during evolution. “So morphological similarities are not a reliable guide for the reconstruction of the genealogical relationships between these organisms,” Wörheide affirms, “and this is certainly also true of the other classes of sponge.”
The new study lays the groundwork for further investigations, in which the researchers will try to pinpoint the times at which the different sponge lineages diverged from one another. To do so, they will exploit the principle of the “molecular clock,” which reflects the fact that the extent of molecular divergence between sequences of the same (“homologous”) genes in any given pair of species provides a measure of the time elapsed since they diverged from one another. By dating divergence times, this strategy promises to enhance our understanding of sponge evolution, and should help to explain why Porifera are among the oldest groups of multicellular organisms still in existence.
Reference:
Astrid Schuster, Dirk Erpenbeck, Andrzej Pisera, John Hooper, Monika Bryce, Jane Fromont, Gert Wörheide. Deceptive Desmas: Molecular Phylogenetics Suggests a New Classification and Uncovers Convergent Evolution of Lithistid Demosponges. PLoS ONE, 2015; 10 (1): e116038 DOI: 10.1371/journal.pone.0116038
The 415-million-year-old fish Janusiscus provides critical evidence for a well-developed external skeleton (shown in blue) in the shared ancestor of bony fishes and cartilaginous fishes such as sharks. Placoderm image courtesy of K Trinajstic. Credit: Oxford University/K Trinajstic
An investigation of a 415 million year-old fish skull strongly suggests that the last common ancestor of all jawed vertebrates, including humans, was not very shark-like. It adds further weight to the growing idea that sharks are not ‘primitive’.
The fossil skull’s external features meant it had always been thought to belong to the bony fishes (osteichthyans), a group which includes familiar fishes such as cod and tuna as well as all land-dwelling creatures with backbones. But when scientists from Oxford University and Imperial College London used X-ray CT scanning to look inside the skull they found the structure surrounding the brain was reminiscent of cartilaginous fishes (chondrichthyans) such as sharks and rays. The fish fossil’s ‘two faces’ led to it being named Janusiscus after the double-faced Roman god Janus.
A report of the research is published in the journal Nature.
‘This 415 million year-old fossil gives us an intriguing glimpse of the ‘Age of Fishes’, when modern groups of vertebrates were really beginning to take off in an evolutionary sense,’ said Dr Matt Friedman of Oxford University’s Department of Earth Sciences, an author of the report. ‘It tells us that the ancestral jawed vertebrate probably doesn’t fit into our existing categories.’
Chondrichthyans have often been viewed as primitive, and treated as proxies for what the ‘ancestral’ jawed vertebrate would have looked like. A key component of this view is the lack of a bony skeleton in cartilaginous fishes.
Janusiscus fish fossil Credit: Oxford University/K Trinajstic
‘The results from our analysis help to turn this view on its head: the earliest jawed vertebrates would have looked somewhat more like bony fishes, at least externally, with large dermal plates covering their skulls,’ said Sam Giles of Oxford University’s Department of Earth Sciences, first author of the report. ‘In fact, they would have had a mix of what are now viewed as cartilaginous- and bony fish-like features, supporting the idea that both groups became independently specialised later in their separate evolutionary histories.’
Dr Friedman said: ‘This mix of features, some reminiscent of bony fishes and others cartilaginous fishes, suggests that humans may have just as many features that you might call ‘primitive’ as sharks.’
The fossil skull was originally found near the Sida River in Siberia in 1972 and is currently held in the Institute of Geology at the Tallinn University of Technology, Estonia. Study author Martin Brazeau of Imperial College London spotted the specimen in an online catalogue and the team decided it would be worth studying in greater detail using modern investigative techniques.
The team then used X-ray CT (computed tomography) to ‘virtually’ cut through the fossil. Different materials attenuate X-rays to different amounts — just as in a hospital X-ray, bones show up brighter than muscles and skin. This same principle can be applied to fossils, as fossilised bone and rock attenuate X-rays to different degrees. This technique was used to build a 3D virtual model of the fossil, enabling its internal and external features to be examined in great detail. Traces left by networks of blood vessels and nerves, often less than 1/100th of a centimetre in diameter, could then be compared to structure in a variety of jawed vertebrate groups, including sharks and bony fishes.
‘Losing your bony skeleton sounds like a pretty extreme adaptation,’ said Dr Friedman, ‘but with remarkable discoveries from China, Janusiscus strongly suggests that that the ancient ancestors of modern sharks and their kin started out just as ‘bony’ as our own ancestors.’
Video
Reference:
Sam Giles, Matt Friedman & Martin D. Brazeau. Osteichthyan-like cranial conditions in an Early Devonian stem gnathostome. Nature, 2015 DOI: 10.1038/nature14065
The Tavurvur Cone in Papua New Guinea was erupting when this image was captured by the Advanced Land Imager on NASA’s Earth Observing-1 (EO-1) satellite on Nov. 30, 2009. The eruption is one that may have contributed to a “warming hiatus.” Credit: Image courtesy of DOE/Lawrence Livermore National Laboratory
The “warming hiatus” that has occurred over the last 15 years has been caused in part by small volcanic eruptions.
Scientists have long known that volcanoes cool the atmosphere because of the sulfur dioxide that is expelled during eruptions. Droplets of sulfuric acid that form when the gas combines with oxygen in the upper atmosphere can persist for many months, reflecting sunlight away from Earth and lowering temperatures at the surface and in the lower atmosphere.
Previous research suggested that early 21st-century eruptions might explain up to a third of the recent warming hiatus.
New research available online in the journal Geophysical Research Letters (GRL) further identifies observational climate signals caused by recent volcanic activity. This new research complements an earlier GRL paper published in November, which relied on a combination of ground, air and satellite measurements, indicating that a series of small 21st-century volcanic eruptions deflected substantially more solar radiation than previously estimated.
“This new work shows that the climate signals of late 20th- and early 21st-century volcanic activity can be detected in a variety of different observational data sets,” said Benjamin Santer, a Lawrence Livermore National Laboratory scientist and lead author of the study.
The warmest year on record is 1998. After that, the steep climb in global surface temperatures observed over the 20th century appeared to level off. This “hiatus” received considerable attention, despite the fact that the full observational surface temperature record shows many instances of slowing and acceleration in warming rates. Scientists had previously suggested that factors such as weak solar activity and increased heat uptake by the oceans could be responsible for the recent lull in temperature increases. After publication of a 2011 paper in the journal Science by Susan Solomon of the Massachusetts Institute of Technology (link is external) (MIT), it was recognized that an uptick in volcanic activity might also be implicated in the warming hiatus.
Prior to the 2011 Science paper, the prevailing scientific thinking was that only very large eruptions — on the scale of the cataclysmic 1991 Mount Pinatubo eruption in the Philippines, which ejected an estimated 20 million metric tons (44 billion pounds) of sulfur — were capable of impacting global climate. This conventional wisdom was largely based on climate model simulations. But according to David Ridley, an atmospheric scientist at MIT and lead author of the November GRL paper, these simulations were missing an important component of volcanic activity.
Ridley and colleagues found the missing piece of the puzzle at the intersection of two atmospheric layers, the stratosphere and the troposphere — the lowest layer of the atmosphere, where all weather takes place. Those layers meet between 10 and 15 kilometers (six to nine miles) above Earth.
Satellite measurements of the sulfuric acid droplets and aerosols produced by erupting volcanoes are generally restricted to above 15 km. Below 15 km, cirrus clouds can interfere with satellite aerosol measurements. This means that toward the poles, where the lower stratosphere can reach down to 10 km, the satellite measurements miss a significant chunk of the total volcanic aerosol loading.
To get around this problem, the study by Ridley and colleagues combined observations from ground-, air- and space-based instruments to better observe aerosols in the lower portion of the stratosphere. They used these improved estimates of total volcanic aerosols in a simple climate model, and estimated that volcanoes may have caused cooling of 0.05 degrees to 0.12 degrees Celsius since 2000.
The second Livermore-led study shows that the signals of these late 20th and early 21st eruptions can be positively identified in atmospheric temperature, moisture and the reflected solar radiation at the top of the atmosphere. A vital step in detecting these volcanic signals is the removal of the “climate noise” caused by El Niños and La Niñas.
“The fact that these volcanic signatures are apparent in multiple independently measured climate variables really supports the idea that they are influencing climate in spite of their moderate size,” said Mark Zelinka, another Livermore author. “If we wish to accurately simulate recent climate change in models, we cannot neglect the ability of these smaller eruptions to reflect sunlight away from Earth.” References:
D. A. Ridley, S. Solomon, J. E. Barnes, V. D. Burlakov, T. Deshler, S. I. Dolgii, A. B. Herber, T. Nagai, R. R. Neely, A. V. Nevzorov, C. Ritter, T. Sakai, B. D. Santer, M. Sato, A. Schmidt, O. Uchino, J. P. Vernier. Total volcanic stratospheric aerosol optical depths and implications for global climate change. Geophysical Research Letters, 2014; 41 (22): 7763 DOI: 10.1002/2014GL061541
Benjamin D. Santer, Susan Solomon, Céline Bonfils, Mark D. Zelinka, Jeffrey F. Painter, Francisco Beltran, John C. Fyfe, Gardar Johannesson, Carl Mears, David A. Ridley, Jean-Paul Vernier, Frank J. Wentz. Observed multi-variable signals of late 20th and early 21st century volcanic activity. Geophysical Research Letters, 2014; DOI: 10.1002/2014GL062366
Research suggests an extra source of electrons was needed to create the massive Here’s Your Chance deposit. Credit: McArthur River Mine
Researchers have advanced the quest to understand how one of Australia and the world’s largest zinc and lead mining deposits was formed.
Covering 2 km2, the Here’s Your Chance (HYC) mine is located in the Middle Proterozoic McArthur Basin, in the Northern Territory.
Mineral deposits like HYC’s are created when sulfate in the ore fluids is reduced to produce lead and zinc sulfides, a process that requires electrons.
Yet researchers investigating the chemistry of HYC’s formation say local sediments may have supplied only around one-third of the electrons required to form the deposit.
Dr Jeffrey Dick from Curtin University says his team looked at the amounts (or ‘budgets’) of carbon, sulfur and electrons required to form a deposit of HYC’s size.
Their study accounted for possible flow and interaction between five conceptually distinct reservoirs: HYC’s un-mineralised shale, the HYC ore deposit, oceanic water, hydrothermal ore-bearing fluids, and external reservoirs, included to allow for the introduction of external reduced carbon or sulfide.
Search for the missing electrons
Dr Dick’s team first explored how many electrons could have been produced in-situ, by oxidation of organic matter within the mine sediments.
“Through mass balance calculations, we explored whether enough organic matter was present to allow for the necessary level of reduction,” Dr Dick says.
“We found that the oxidisation of in-situ organic carbon provides at most one-third of the [electrons] needed to reduce sulfate to form the known quantity of ore minerals at HYC.”
Dr Dick says this minimal contribution by in-situ organic matter suggests the introduction of another source of electrons, in the form of reduced carbon, or an alternative source of reduced sulfur.
He says the reduced sulfur could have come from deep seawater, which may have become progressively more sulfidic after 1.8 GA (1.8 billion years ago) and perhaps contacted localised sulphate in the ore fluids to form extra sulfide.
The missing electrons may also have been provided by natural gas containing significant amounts of hydrogen sulfide, a hydrocarbon reservoir in the subsurface, or hydrocarbons migrating from deep within the earth.
Researchers say evidence at HYC of aromatic hydrocarbons—thought to form deep underground at temperatures above 200oC—supports the idea of migration.
While the mystery of the missing electrons has not been definitively solved, Dr Dick says the study’s investigative framework has proven valid and can help in understanding other lead-zinc deposits worldwide.
Reference:
“Combined sulfur, carbon and redox budget constraints on genetic models for the Here’s Your Chance Pb–Zn deposit, Australia.” GeoResJ, Volumes 3–4, September–December 2014, Pages 19-26, ISSN 2214-2428, dx.doi.org/10.1016/j.grj.2014.09.001.
Note : The above story is based on materials provided by Science Network WA.
This image was taken during the August 2014 eruption of Tavurvur in Papua New Guinea. Lawrence Livermore researchers identified the climatic signals of some of the larger early 21st-century eruptions (such as the October 2006 eruption of Tavurvur).
The “warming hiatus” that has occurred over the last 15 years has been partly caused by small volcanic eruptions.
Scientists have long known that volcanoes cool the atmosphere because of the sulfur dioxide that is expelled during eruptions. Droplets of sulfuric acid that form when the gas combines with oxygen in the upper atmosphere can persist for many months, reflecting sunlight away from Earth and lowering temperatures at the surface and in the lower atmosphere.
Previous research suggested that early 21st century eruptions might explain up to a third of the recent “warming hiatus.”
New research available online in the journal Geophysical Research Letters (GRL) further identifies observational climate signals caused by recent volcanic activity. This new research complements an earlier GRL paper published in November, which relied on a combination of ground, air and satellite measurements, indicated that a series of small 21st century volcanic eruptions deflected substantially more solar radiation than previously estimated.
“This new work shows that the climate signals of late 20th and early 21st century volcanic activity can be detected in a variety of different observational data sets,” said Benjamin Santer, a Lawrence Livermore National Laboratory scientist and lead author of the study.
The warmest year on record is 1998. After that, the steep climb in global surface temperatures observed over the 20th century appeared to level off. This “hiatus” received considerable attention, despite the fact that the full observational surface temperature record shows many instances of slowing and acceleration in warming rates. Scientists had previously suggested that factors such as weak solar activity and increased heat uptake by the oceans could be responsible for the recent lull in temperature increases. After publication of a 2011 paper in the journal Science by Susan Solomon of the Massachusetts Institute of Technology (MIT), it was recognized that an uptick in volcanic activity might also be implicated in the “warming hiatus.”
Prior to the 2011 Science paper, the prevailing scientific thinking was that only very large eruptions – on the scale of the cataclysmic 1991 Mount Pinatubo eruption in the Philippines, which ejected an estimated 20 million metric tons (44 billion pounds) of sulfur – were capable of impacting global climate. This conventional wisdom was largely based on climate model simulations. But according to David Ridley, an atmospheric scientist at MIT and lead author of the November GRL paper, these simulations were missing an important component of volcanic activity.
Ridley and colleagues found the missing piece of the puzzle at the intersection of two atmospheric layers, the stratosphere and the troposphere – the lowest layer of the atmosphere, where all weather takes place. Those layers meet between 10 and 15 kilometers (six to nine miles) above the Earth.
Satellite measurements of the sulfuric acid droplets and aerosols produced by erupting volcanoes are generally restricted to above 15 km. Below 15 km, cirrus clouds can interfere with satellite aerosol measurements. This means that toward the poles, where the lower stratosphere can reach down to 10 km, the satellite measurements miss a significant chunk of the total volcanic aerosol loading.
To get around this problem, the study by Ridley and colleagues combined observations from ground-, air- and space-based instruments to better observe aerosols in the lower portion of the stratosphere. They used these improved estimates of total volcanic aerosols in a simple climate model, and estimated that volcanoes may have caused cooling of 0.05 degrees to 0.12 degrees Celsius since 2000.
The second Livermore-led study shows that the signals of these late 20th and early 21st eruptions can be positively identified in atmospheric temperature, moisture and the reflected solar radiation at the top of the atmosphere. A vital step in detecting these volcanic signals is the removal of the “climate noise” caused by El Niños and La Niñas.
“The fact that these volcanic signatures are apparent in multiple independently measured climate variables really supports the idea that they are influencing climate in spite of their moderate size,” said Mark Zelinka, another Livermore author. “If we wish to accurately simulate recent climate change in models, we cannot neglect the ability of these smaller eruptions to reflect sunlight away from Earth.”
Some of the purported “swimmers” in the Cave of the Swimmers, Egypt. Credit: NASA Photo/Chris McKay
Life imitates art. And sometimes science does the same.
Seven thousand year-old rock paintings in the Sahara desert have, somewhat serendipitously, helped uncover evidence of ancient lake beds.
Researchers discovered the mineral remnants of the lake while studying a region well-known for its rock art. The most famous example is the Cave of the Swimmers, which provided a setting in the movie “The English Patient.” The drawings in the cave depict humans that appear to be swimming, floating and diving. And yet this area in southwestern Egypt is one of the driest in the world.
The generally-accepted explanation is that the climate was much wetter in the past, supporting not only the possibility of a swimming hole, but also abundant animal life, such as cows, giraffes and ostriches, which were also drawn or carved into the region’s rocks.
Scientists have previously found support for this local change in climate in ancient lake beds and other geologic data, but most of these lakes pre-date the rock art by many thousands of years. Until now, no one had identified any evidence of a relatively recent, semi-permanent lake that could have served as a swimming hole for the local rock artists.
“Indeed, we found that there were lakes not far from the Cave of the Swimmers,” says Chris McKay from the NASA Ames Research Center.
Earlier this year, McKay and his colleagues—Margarita Marinova from the Bay Area Environmental Research Institute and Nele Meckler of ETH Zurich—reported on carbonate deposits lining the walls of two neighboring valleys in the Gebel Uweinat region, which is about 200 kilometers south of the Cave of the Swimmers.
“The deposits look like a ‘bathtub ring’ around the canyon walls,” McKay says.
The ring-shape and mineral content of the deposits imply that they formed in shallow water along a lake shoreline. From carbon dating, McKay and his colleagues estimate that the two inferred lakes existed about 8,100 and 9,400 years ago, respectively.
The age of the lakes seems about right that one could bravely speculate that the prehistoric men or women who decorated the Cave of the Swimmers either knew of the lakes or perhaps even swam in one of them on a wandering voyage.
The research—presented in the Journal of African Earth Sciences—was partly funded by the NASA Astrobiology Program.
The Cave of the Swimmers has captivated imaginations ever since it was discovered by the Hungarian explorer László Almásy in 1933. The shallow cave’s paintings are about 7,000 years old, give or take a thousand years, and show human figures performing what looks like a kind of Neolithic doggy paddle.
Confronted by the seeming inconsistency of swimmers in a desert landscape, Almásy hypothesized that the artists were realistically depicting their surroundings and that the climate had in fact been wetter back then.
The cave and Almásy himself inspired Michael Ondaatje’s book “The English Patient,” and the film that followed with the same name.
However, it should be noted that researchers now question the original interpretation of “swimming.”
“The ‘swimmers’ move towards ‘headless beasts’ in a straight line, more as if floating in air than swimming” says Andras Zboray, a Sahara explorer and rock art researcher. “They are clearly symbolic, as are the beasts, with an unknown meaning.”
Rock art depicting a white cow. Credit: NASA Photo/Chris McKay
Still, the idea that water was much more abundant in this part of the Sahara several thousand years ago is supported by other prehistoric art in the region. Other caves and rocks show scenes of pastoral animals, which would have been unable to survive in the current dry conditions.
“Both [of the newly-discovered] lakes are located in areas with an exceptionally rich concentration of rock art sites in the immediate vicinity, and I suspect this cannot be a coincidence,” Zboray says.
Lake residents
As compelling as this connection between art and past climate may be, McKay did not venture into the Sahara to study ancient human artifacts, nor to look for dried-up lakes. He and co-author Marinova went to the Egyptian desert to study rock-clinging microbes with the purpose of finding out how these organisms can survive under such extreme conditions, and whether they can give us any clues to potential life on Mars.
“Our scientific interest is the dry limit of photosynthesis, so we wanted to go to the driest part of the Sahara,” McKay says.
But exploring this harsh environment is logistically challenging. For this reason, McKay and Marinova joined an archaeology group led by Zboray that was going to Gebel Uweinat to study the local rock art.
During one of their excursions, McKay noticed mineral deposits that reminded him of other work he has done on lake sediments. The geologic features partially resemble dried-up sponges, and were found in two valleys separated by about 5 kilometers.
McKay and his colleagues took a few samples and measured the mineral composition to be primarily carbonate. The horizontal alignment of the deposits and their unique structure indicates that they formed in long-term standing water. The team concluded that each valley must have supported a relatively stable lake.
“The size of the lakes would probably have been large enough to do laps,” McKay says.
Zboray finds fascinating the confirmation of standing bodies of freshwater in Gebel Uweinat roughly 9,000 year ago, but it raises a number of yet unanswered questions.
“The obtained dates are surprisingly old, and appear to considerably pre-date the bulk of the rock art,” Zboray says. The caves in the surrounding area have abundant cattle paintings that are dated as 6,500 to 5,500 years old.
“So there is a clear temporal disconnect,” he says.
Zboray is also puzzled by the local geography. The lakes could have formed from a natural dam, and they could have been fed by rainfall. However, in this case, the lake levels would have likely gone up and down with strong evaporation and infrequent rainfall.
“One plausible explanation is that the lakes were fed by some artesian source that could keep them at the same level for an extended time period, only limited by the height of the barrier blocking the valley,” Zboray says.
He has plans to go back to the area to better map out the extent of the deposits and to look for remnants of the presumed barrier.
Microbial rock art
The mineral deposits themselves tell a story about life in and around the lake.
The carbonate has a morphologically-distinct structure that typically forms only in water that contains microbes. The organisms alter the pH, affecting how the carbonate precipitates out of solution.
“The carbonate is a macroscopic remnant of microscopic life,” McKay explains.
These biologically-triggered formations, or “microbialites,” are found around the world at places such as Pavilion Lake in Canada and Lake Alchichica in Mexico.
Darlene Lim from NASA Ames agrees that the deposits found by McKay’s group are similar to the microbialites she studies as the principal investigator for the Pavilion Lake Research Project.
“The fundamental difference between the two is that the Pavilion Lake microbialites can grow to a larger size, and at times they are less consolidated than those reported in the waters of Gebel Uweinat,” Lim says. “However, the microbialites described by Marinova et al. may have undergone some erosion, and as such their maximum size remains unknown.”
Astrobiologists are very interested in microbialites as they could be a possible red flag for past life on Mars.
“We are not going to find dinosaur fossils on Mars,” McKay says.
But a bathtub ring of carbonates is something that one of our rovers might potentially roll up to, he says.
Lim, however, is not convinced a rover has the capabilities to deal with the serendipitous nature of scientific discovery.
“What I hope is that someday soon a human will be able to apply their training, knowledge, and instincts, to find their way to a discovery on Mars that mirrors what Marinova et al. found in the Gebel Uweinat region,” Lim says.
Note : The above story is based on materials provided by Astrobio.net This story is republished courtesy of NASA’s Astrobiology Magazine. Explore the Earth and beyond at www.astrobio.net .
UF geochemist Andrea Dutton (right) and Jody Webster of the University of Sydney (left) study a limestone outcrop containing fossil corals in Seychelles.
The balmy islands of Seychelles couldn’t feel farther from Antarctica, but their fossil corals could reveal much about the fate of polar ice sheets.
About 125,000 years ago, the average global temperature was only slightly warmer, but sea levels rose high enough to submerge the locations of many of today’s coastal cities. Understanding what caused seas to rise then could shed light on how to protect those cities today.
By examining fossil corals found on the Indian Ocean islands, University of Florida geochemist Andrea Dutton found evidence that global mean sea level during that period peaked at 20 to 30 feet above current levels. Dutton’s team of international researchers concluded that rapid retreat of an unstable part of the Antarctic ice sheet was a major contributor to that sea-level rise.
“This occurred during a time when the average global temperature was only slightly warmer than at present,” Dutton said.
Dutton evaluated fossil corals in Seychelles because sea level in that region closely matches that of global mean sea level. Local patterns of sea-level change can differ from global trends because of variations in the Earth’s surface and gravity fields that occur when ice sheets grow and shrink.
In an article published in the January 2015 issue of Quaternary Science Reviews, the researchers concluded that while sea-level rise in the Last Interglacial period was driven by the same processes active today—thermal expansion of seawater, melting mountain glaciers and melting polar ice sheets in Greenland and Antarctica—most was driven by polar ice sheet melt. Their study, partially funded by the National Science Foundation, also suggests the Antarctic ice sheet partially collapsed early in that period.
“Following a rapid transition to high sea levels when the last interglacial period began, sea level continued rising steadily,” Dutton said. “The collapse of Antarctic ice occurred when the polar regions were a few degrees warmer than they are now—temperatures that we are likely to reach within a matter of decades.”
Several recent studies by other researchers suggest that process may have already started.
“We could be poised for another partial collapse of the Antarctic ice sheet,” Dutton said.
Reference:
Andrea Dutton, Jody M. Webster, Dan Zwartz, Kurt Lambeck, Barbara Wohlfarth. Tropical tales of polar ice: evidence of Last Interglacial polar ice sheet retreat recorded by fossil reefs of the granitic Seychelles islands. Quaternary Science Reviews, 2015; 107: 182 DOI: 10.1016/j.quascirev.2014.10.025
This 59.6-carat pink diamond was auctioned by Sotheby’s in 2013 Credit : BBC
They’re one of the world’s rarest jewels – but nobody knows for certain why pink diamonds are pink.
That hasn’t stopped investors from snapping them up at auction and sending prices skyrocketing. In October a new world record was set at a Sotheby’s sale in Hong Kong when an 8.41-carat pink diamond sold for $17,768,041 (£11,438,714) – more than $2.1m (£1.8m) a carat.
“Everybody’s talking about them, and everybody loves them,” says Jeffrey Post, curator of the National Gem and Mineral Collection at the Smithsonian’s National Museum of Natural History in Washington, DC. “Yet you can’t tell people why they’re pink.”
Other diamonds get their colour from chemical impurities that absorb light. Yellow diamonds contain traces of nitrogen, and blue diamonds contain boron. But no similar impurities have been found in pink diamonds, leading scientists to speculate that the colour may be the result of some kind of seismic shock that altered the stone’s molecular structure.
It’s now hoped that a cache of brown and pink diamonds from the Argyle mine in Western Australia may solve the mystery. The mine, owned by Rio Tinto, is the world’s largest source of pink diamonds, even though they’re so rare that only a few are produced each year.
As well as revealing what makes them pink, scientists hope that studying the diamonds will tell them more about the history of the planet.
Diamonds are the Earth’s messengers, says Post. “They come from a hundred miles below the surface and tell us about a part of the Earth that we can’t visit. They’re also giving us a peek back in time because most diamonds formed about two to three billion years ago.
“Each one is a time capsule, and the pink diamonds, because they’re different from all the other diamonds, have a different part of the story to tell.”
Scientists have already examined the Argyle diamonds using a mass spectrometer to try to find any trace of impurities that may be causing the pink colour. The machine agitates the diamonds and analyses the chemical structure of the atoms that are released.
“There is no impurity that we’ve been able to associate so far with the pink colour in diamonds,” says Post. “Spectroscopic measurements don’t show you any additional features that you can ascribe to a particular colouring agent.”
They’ve also used a focused ion beam to cut a tiny trench in the surface of the diamonds and remove a sliver that can be measured under a powerful electron microscope. They’ve discovered that most pink diamonds are not uniformly pink but have pink zones that alternate with clear areas.
The zones, known as twin planes, were formed by some kind of shock – possibly the result of volcanic activity that propelled the diamonds to the surface or from something that happened to them as they were being formed deep underground.
“The twin plane itself should not give rise to colour,” says Post. “But we think when those twin planes form, and slide back and forth, one against the other like a fault plane, that certain kinds of defects formed. The defects give us the pink colour. But what we’ve not been able to do yet is find the specific kind of defect.”
Although pink diamonds are among the most valuable jewels today, 20 years ago they were little more than a geological curiosity. Sales have been driven by savvy marketing and a growing appreciation of their uniqueness.
“It really comes down to the rarity,” says Richard Revez, a gem expert at Florida-based Kravit Estate Department. “When you talk about coloured diamonds, they’re already in the elite 1% produced in the world. Pink diamonds are the 1% of the 1%.”
He says the most sought-after diamonds are actually red, but orange, green, blue and yellow are highly desirable. An orange diamond attracted the highest price paid per carat for any diamond at auction last year, selling for $35m, or $2.4m a carat.
“We’ve craved diamonds for millennia,” says Revez. The first gems were probably discovered on river banks in India, but their existence is recorded in Greek and Roman history. “It was believed there was a vein that ran directly from the heart to the ring finger – that’s why we wear (diamonds) on our ring fingers. And Cupid’s arrows were tipped with diamonds to pierce the heart easier,” he says.
Archduke Maximilian of Austria is believed to have started the tradition of diamond engagement rings among the upper classes when he presented one to Mary of Burgundy in 1477.
But it wasn’t until the 1950s that international standards to grade diamonds were set by the Gemological Institute of America (GIA), a classification system that is still used today.
But only science can reveal why pink diamonds are pink.
Pink diamonds can be artificially created, says the Smithsonian’s Post. And the only way to tell if it’s a synthetic stone is to understand what causes the colour to occur naturally.
“Then I can tell you for sure that that is a diamond that came out of the earth as opposed to one that came out of somebody’s laboratory. It can make the difference of millions of dollars in the value of a single diamond, knowing whether it is a natural pink or not.”
Note : The above story is based on materials provided by BBC News. The original article was written by Jane O’Brien.
Global rare earth element production (1 kt=106 kg) from 1950 through 2000, in four categories: United States, almost entirely from Mountain Pass, California; China, from several deposits; all other countries combined, largely from monazite-bearing placers; and global total. Four periods of production are evident: the monazite-placer era, starting in the late 1800s and ending abruptly in 1964; the Mountain Pass era, starting in 1965 and ending about 1984; a transitional period from about 1984 to 1991; and the Chinese era, beginning about 1991. Credit : U.S. Geological Survey
RioSol SAC LLC and Compania Minera Rio Sol SAC (“RioSol” or “The Company”) on Dec. 30, 2014 announced a significant rare earth element and poly-metallic claim discovery in Peru, with reports indicating the 10-kilometer claim as among the largest rare earth claims in Peru containing both light rare earth elements (LREEs) and heavy rare earth elements and metals (HREEs).
Third-party geology and geochemical analysis indicates the claim is the largest in Peru, with further exploration warranted to further delineate the size and scale of the claim.
The geology consultants leading the project were Rildo Oscar Rodriguez and a Peruvian rare earth expert, both of Lima. According to Mr. Rodriguez, “The claim is one of the newest rare earth finds in all of Latin America that contains both light and heavy rare earth elements and metals, as well as copper, zinc, aluminum and other base metals. It proves that the potential for rare earth elements exists outside of China with significant opportunity for development of new production in a mining-friendly country.”
Currently, approximately 90-95 percent of rare earth elements are located in China. Having a supply source in the Americas for commodities used today and in the future will be important for geographic diversity and commercial competition.
Over the past two years, RioSol has been testing the claim, initially focused on base metals. However, rare earths were discovered in recent field explorations and assay results, and further testing was conducted. Both the rare earth geologist and RioSol general manager Max Cruz will be presenting the results of the discovery at PROEXPLO 2015, the 9th International Congress of Prospectors and Explorers in May.
The claim area is located approximately 95 kilometers northwest of Cusco, Peru.
Rare earth elements are a group of 17 chemical elements that occur together in the periodic table. The group consists of yttrium and the 15-lanthanide elements (lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium). Scandium is found in most rare earth element deposits and is sometimes classified as a rare earth element.
The rare earth elements are all metals, and the group is often referred to as “rare earth metals.” These metals have many similar properties and that often causes them to be found together in geologic deposits. They are also referred to as “rare earth oxides” because many of them are typically sold as oxide compounds.
Seismologists interpret the shaking from the original Beast Quake on Jan. 8, 2011, when Seahawks fans literally rocked the stadium. Credit: Pacific Northwest Seismic Network
It’s not just the football players who have spent a year training. University of Washington seismologists will again be monitoring the ground-shaking cheers of Seahawks fans, this year with a bigger team, better technology and faster response times.
Scientists with the Pacific Northwest Seismic Network will install instruments this Thursday to provide real-time monitoring of the stadium’s movement during the 2015 NFL playoffs.
This year, the UW researchers have also upped their game. A new QuickShake tool will provide a faster connection between the sensors and the website. This Saturday will be the first test of the software that displays vibrations within three seconds — five to 10 times faster and more reliably than readings from the same sensors installed last year.
The Pacific Northwest Seismic Network monitors earthquake and volcanic activity throughout the region. Network scientists first got interested in football when a seismometer a block away from the stadium showed vibrations during Marshawn Lynch’s legendary Jan. 8, 2011, touchdown run. The resulting seismograph became a celebrity in its own right and coined the term “Beast Quake.”
After a couple of quieter years, the group got permission last year to place two strong-motion earthquake sensors inside the stadium. The project was a huge hit and the group added a third sensor for the 2014 playoff game.
A Beast Quake happens when the energetic jumping and stomping of so many fans at once shakes the stadium and reverberates through the surrounding soil. Seahawks fans also generate record-breaking noise, of course, but sound waves don’t rock the building. A guaranteed shaking event with significant public interest is a great test case.
“We’re mostly interested in the speed and the reliability of the communications,” said John Vidale, a UW professor of Earth & space sciences and director of the seismic network. “It’s hard to simulate thousands of people using this tool all at once. When we can get a lot of people looking, we can see problems that we’d encounter during an actual earthquake.”
For fans at home, the faster data transfer means that TV viewers may get a tipoff to a big play they’ll see on the screen after the 10-second broadcast delay. The researchers have dubbed them “Early Football Rowdiness Warnings.”
The foot-stomping is a real-world test of technology to detect the bigger shaking that originates underground. The seismic group is working with the U.S. Geological Survey to offer early warnings for the Pacific Northwest that could provide tens of seconds to several minutes’ notice of an incoming strong shaking. This year some public agencies and large businesses will have a first chance to try out the system that will eventually be available to the public.
“The Seahawks experiment should provide us and the Internet-connected public with a feel for the minimum time early warning might provide,” said Steve Malone, a UW professor emeritus of Earth & space sciences. “In this case it’s football fan activity that generates a signal as a warning for what shows up on TV some seconds later. In the future, it might be seconds to minutes of warning after an earthquake starts.”
This weekend the group will be beefing up its social-media presence to post updates and respond to questions during the game. That also helps get ready for an emergency situation.
“During the rumblings on Mt. St. Helens a decade ago there was a huge influx of Web visits and phone calls,” Malone said. “Now with social media, it’s a whole new ballgame. We’ve got to learn how to deal with that because it’s going to snow us over if we’re not prepared.”
The group will have more staff monitoring social media during the game, and more robust websites that they hope won’t slow down or crash during heavy traffic.
On the scientific side, they hope to explore the different readings between the three sensors placed at different levels. They also hope to explain some mysterious patterns of shaking during commercial breaks, what one researchers hypothesizes may be a “dance quake.”
Several researchers will be at the UW campus lab Saturday monitoring the sensors. Two group members will be at the stadium providing eyes on the ground to help explain what could be causing any unusual spikes. They will be rooting for a victory for the Seahawks — and for science.
“We’re developing these new Web tools, and monitoring the game really motivates everyone to get excited,” Vidale said, “and we’re rooting for a second helping of roars and rumbles against the Packers or Cowboys to perfect the system.”
Note : The above story is based on materials provided by University of Washington. The original article was written by Hannah Hickey.
Dr Kyle Baldwin. Credit: Image courtesy of University of Nottingham
Using magnetic levitation to imitate weightlessness, researchers led by physicists at The University of Nottingham have manufactured solid wax models of splash form tektites. Dr Kyle Baldwin from the School of Physics and Astronomy, said: “These wax models provide the first direct experimental validation for numerical models of the equilibrium shapes of spinning droplets. This research is of importance to fundamental physics and also to study of tektite formation.”
Splash form tektites are tiny pieces of natural glass created out of spinning drops of molten rock flung from the earth during an extra-terrestrial impact — when the earth is hit by asteroids or comets. They come in a myriad of shapes — from dumbbell to doughnut — and the formation of these shapes has been the subject of scientific investigation for centuries. Using magnetic levitation to imitate weightlessness, researchers led by physicists at The University of Nottingham have manufactured solid wax models of these shapes. Dr Kyle Baldwin from the School of Physics and Astronomy, said: “These wax models provide the first direct experimental validation for numerical models of the equilibrium shapes of spinning droplets. This research is of importance to fundamental physics and also to study of tektite formation.”
Until now the shapes of rapidly spinning, highly deformed droplets have been derived entirely from numerical simulations. It is hoped this new experimental technique can be used to better reproduce and understand tektite formation. Their research — Artificial tektites: an experimental technique for capturing the shapes of spinning drops — funded by the Engineering and Physical Sciences Research Council (EPSRC) is published today in the online, open access journal Scientific Reports. The video can be seen here.
A droplet of liquid in space is spherical, but spin it and it forms all kinds of shapes from squashed balls to bone-shaped, depending on its rate of spin. Atomic nuclei, planets, including planet Earth, stars, and even black holes are deformed by their spin for the same reasons as a liquid droplet, as are tektites.
Just back from presenting his research at the 2014 American Geophysical Union’s Fall Meeting — the largest Earth and space science meeting in the world — Dr Kyle Baldwin said: “As you can imagine the creation of these tiny objects is difficult to reproduce in the lab. There aren’t many materials that can contain molten rock, and even then you need to spin and cool a single droplet of it simultaneously.”
These tiny glass objects are found mainly in Australasia, Central Europe, North America and the Ivory Coast — in areas associated with extra-terrestrial impacts.
When an asteroid hits the Earth, it creates a large, very hot, zone of impact material. Under very specific impact conditions, this rock melts and is splashed out in all directions. Exactly what these conditions are remains a topic of debate today. These droplets of splashed rock often have rotation imparted by the impact. The act of rotation changes the shape of the drop, depending on how fast it is spinning. It deforms them towards a more flattened sphere, and then eventually to a “dumb-bell” shape as it becomes unstable and pulls apart.
The drops of molten rock spin, change shape, but then crucially, due to the fact that they are cooling as they travel through the atmosphere, solidify into the shape that they formed. Some of these shapes then survive impact with the Earth and are later collected by teams of geologists and studied to examine both the type of rock that the asteroid impacted and the age of the impacted the onlinrock, to correlate with known impact sites and prehistoric extinction events, or find impact sites that have not yet been discovered.
Dr Baldwin said: “What I have done is realise that, using magnetic levitation and drops of wax, you can artificially recreate this process. By melting the wax on a hot plate, pipetting it into the magnetic field, spinning it up and then allowing it to cool, we can recreate some of the conditions that tektites are under as they form. We have primarily used this technique to measure the theoretical shapes of spinning drops, something that has never been done experimentally.”
Dr Baldwin entered this field of research as a postdoc. Working alongside Dr Richard Hill they began looking into levitating and spinning droplets. Using diamagnetic levitation to counteract the gravitational force on the droplet they were able to manufacture ‘artificial tektites’ from spinning molten wax droplets.
Dr Baldwin said: “You could effectively remove gravity by going into orbit, or you could take a parabolic flight but it wouldn’t be long enough. We use super conducting magnets to levitate liquids that are diamagnetic.”
Dr Hill, also from the School of Physics and Astronomy at The University of Nottingham, has been interested in the shapes formed by spinning droplets for some time. Together with Professor Laurence Eaves he published a paper in 2008 on the observation of ‘three-lobed’ or ‘triangular’ spinning droplets.
He said: “Kyle started working with me on this project just over two years ago. When he arrived, he had the brilliant idea of levitating molten wax and spinning it as it solidified, to capture its shape. We saw that the measurements could be used to validate numerical models of highly deformed spinning liquid droplets, relevant to nuclear physics and also to rapidly spinning astronomical objects.”
The research was carried out in collaboration with Professor Samuel Butler from the Department of Geological Sciences at the University of Saskatchewan, Canada. Professor Butler has previously published papers on simulating tektite formation. He provided supporting simulation evidence that the shapes created by Dr Baldwin were the true equilibrium shapes of spinning liquid droplets allowed them to compare their results, sophisticated modern numerical simulations and calculations from literature.
Reference:
Kyle A. Baldwin, Samuel L. Butler, Richard J. A. Hill. Artificial tektites: an experimental technique for capturing the shapes of spinning drops. Scientific Reports, 2015; 5: 7660 DOI: 10.1038/srep07660
