 |
|
Antarctic research helps shed light on climate change on Mars
August 29, 2008Researchers examining images of gullies on the flanks of craters on Mars say they formed as recently as a few hundred thousand years ago and in sites once occupied by glaciers. The features are eerily reminiscent of gullies formed in Antarctica's mars-like McMurdo Dry Valleys.
The parallels between the Martian gullies and those in Antarctica's McMurdo Dry Valleys were made using the latest high-resolution images and technology from satellites orbiting Mars to observe key details of their geological setting.
On Mars, the gullies appear to originate from cirque-like features high on pole-facing crater-interior walls, especially those within the Newton crater, 40°S, examined for the study. In addition to the cirque-like features, the evidence cited for former glaciation includes bowl-shaped depressions fringed by lobate, viscous-flow deposits that extend well out onto the crater floor.
"These bowl-shaped depressions reflect the former location of relatively pure glacier ice," noted David R. Marchant, an Associate Professor of Earth Sciences at Boston University, and co-author of the study published in the August 25th issue of the Proceedings of the National Academy of Sciences with James W. Head of Brown University, lead author, and Mikhail A. Kreslavsky of the University of California, Santa Cruz.
As conditions on Mars shifted toward reduced snowfall at this site, clean ice on the crater wall sublimated, leaving a hole, whereas ice containing appreciable rock-fall debris out on the crater floor became covered with thin rubble, preventing complete volatile loss.
But even as the last glaciers vanished, minor snow likely continued to fall. "This late-stage snow could accumulate in depressions on the crater wall and, in favorable microclimate settings, melt to produce the observed gullies and fans," said Marchant.
"The results", he said, "are exciting because they establish a spatial link between recent gullies and accumulation of glacier ice, strengthening the case for surface melt water flow in the formation of gullies on Mars".
Other candidate processes include dry debris flows and melting of shallow ground ice, but the sequence of events demonstrating recent snowfall in Newton Crater make surface melting of snow banks an appealing choice. In fact, both Marchant and Head have observed similar processes at work in the development of modern gullies within some of the coldest and driest regions of Antarctica.
The authors conclude that changes in the rate and accumulation of snow in Newton Crater are likely related to changes in the inclination of Mars' spin access, or obliquity.
At obliquities even greater than those postulated for glaciation of Newton Crater, the same authors and colleagues postulated even larger-scale mountain glaciation near the equator, on and extending out from the Tharsis volcanoes.
The evidence suggests a link between obliquity, mid-latitude glaciation, and gully formation on Mars. Rather than being a dead planet, the new data are consistent with dynamic climate change on Mars, and with episodes of alpine glaciation and melt water formation in the recent past that rival modern alpine glaciation and gully formation in the coldest and driest mountains of Antarctica.
Boston University
"These bowl-shaped depressions reflect the former location of relatively pure glacier ice," noted David R. Marchant, an Associate Professor of Earth Sciences at Boston University, and co-author of the study published in the August 25th issue of the Proceedings of the National Academy of Sciences with James W. Head of Brown University, lead author, and Mikhail A. Kreslavsky of the University of California, Santa Cruz.
As conditions on Mars shifted toward reduced snowfall at this site, clean ice on the crater wall sublimated, leaving a hole, whereas ice containing appreciable rock-fall debris out on the crater floor became covered with thin rubble, preventing complete volatile loss.
But even as the last glaciers vanished, minor snow likely continued to fall. "This late-stage snow could accumulate in depressions on the crater wall and, in favorable microclimate settings, melt to produce the observed gullies and fans," said Marchant.
"The results", he said, "are exciting because they establish a spatial link between recent gullies and accumulation of glacier ice, strengthening the case for surface melt water flow in the formation of gullies on Mars".
Other candidate processes include dry debris flows and melting of shallow ground ice, but the sequence of events demonstrating recent snowfall in Newton Crater make surface melting of snow banks an appealing choice. In fact, both Marchant and Head have observed similar processes at work in the development of modern gullies within some of the coldest and driest regions of Antarctica.
The authors conclude that changes in the rate and accumulation of snow in Newton Crater are likely related to changes in the inclination of Mars' spin access, or obliquity.
At obliquities even greater than those postulated for glaciation of Newton Crater, the same authors and colleagues postulated even larger-scale mountain glaciation near the equator, on and extending out from the Tharsis volcanoes.
The evidence suggests a link between obliquity, mid-latitude glaciation, and gully formation on Mars. Rather than being a dead planet, the new data are consistent with dynamic climate change on Mars, and with episodes of alpine glaciation and melt water formation in the recent past that rival modern alpine glaciation and gully formation in the coldest and driest mountains of Antarctica.
Boston University
Glaciation Current Events and Glaciation News RSSWhy is Greenland covered in ice?
There have been many reports in the media about the effects of global warming on the Greenland ice-sheet, but there is still great uncertainty as to why there is an ice-sheet there at all.
New evidence implicates humans in prehistoric animal extinctions
Research led by UK and Australian scientists sheds new light on the role that our ancestors played in the extinction of Australia's prehistoric animals. The study, published this week in the journal Proceedings of the National Academy of Sciences of the USA, provides the first evidence that Tasmania's giant kangaroos and marsupial 'rhinos' and 'leopards' were still roaming the island when humans first arrived.
Glaciers Reveal Martian Climate Has Been Recently Active
The prevailing thinking is that Mars is a planet whose active climate has been confined to the distant past. About 3.5 billion years ago, the Red Planet had extensive flowing water and then fell quiet - deadly quiet. It didn't seem the climate had changed much since.
Low oxygen and molybdenum in ancient oceans delayed evolution of life by 2 billion years
A deficiency of oxygen and the heavy metal molybdenum in the ancient deep ocean may have delayed the evolution of animal life on Earth by nearly two billion years, a study led by UC Riverside biogeochemists has found.
Evidence of glaciation in 'super greenhouse' world
Large ice-sheets existed on Earth about 91 million years ago, during one of the warmest periods since life began, an international team of scientists reports this week.
A warming climate can support glacial ice
New research challenges the generally accepted belief that substantial ice sheets could not have existed on Earth during past super-warm climate events.
The sea-ice is getting thinner - A closer look at the climate and ecosystem of the Arctic Ocean
Large areas of the Arctic sea-ice are only one metre thick this year, equating to an approximate 50 percent thinning as compared to the year 2001.
Ice Age survivors in Iceland
Many scientists believe that the ice ages exterminated all life on land and in freshwater in large parts of the Northern Hemisphere, especially on ocean islands such as Iceland.
Melting of the Greenland ice cap may have consequences for climatic change
According to two international-research studies on the last ice age, studies with the participation of Dr Rainer Zahn, research professor in the ICREA at the UAB Institute of Environmental Science and Technology (ICTA), before the great ice sheets of the Arctic Ocean began to melt, early sporadic episodes of melting of the old ice sheet which covered the British Isles had already begun to affect the circulation of the ocean currents, which played a key role in the climatic stability of the planet.
Finding an answer to Darwin's Dilemma
The sudden appearance of large animal fossils more than 500 million years ago - a problem that perplexed even Charles Darwin and is commonly known as "Darwin's Dilemma" - may be due to a huge increase of oxygen in the world's oceans, says Queen's paleontologist Guy Narbonne, an expert in the early evolution of animals and their ecosystems.
More Glaciation Current Events and Glaciation News Articles
| Glaciers and Glaciation by Douglas I Benn, David J.A. Evans Glaciers and Glaciation is the classic textbook for all students of glaciation. Stimulating and accessible, it has established a reputation as a comprehensive and essential resource. In this new edition, the text, references, and illustrations have been thoroughly updated to give today's reader an up-to-the minute overview of the nature, origin, and behavior of glaciers and the geological and... | |
| Living Ice: Understanding Glaciers and Glaciation by Robert P. Sharp Far from being a passive chunk of ice, a glacier is a dynamic system, sensitive to its surroundings and constantly changing to adapt to its environment. This work aims to increase our knowledge and understanding of glacial activity and... | |
 | Glaciers & Glaciation by Douglas I./ Evans, David J. A. Benn |
 | Glaciation (Salt Modern Poets) by William Stone 'Sometimes you read collections that in their ambition and concerns alert the mind to the possibility of obtaining a new perspective on what else is being written all around us and this book is such a collection ...' These words written by the poet Paul Stubbs, announce to an English readership the power, originality and rare visionary elements to be found in this remarkable debut collection from... |
| Mountain Glaciation (Paper Only) by Owen | |
| The glaciations and the prehistoric ages (Bulletin of the Madras Government Museum) by M. D Raghavan | |
| Neanderthals and Modern Humans in the European Landscape of the Last Glaciation (Mcdonald Institute Monographs) What role did Ice Age climate play in the demise of the Neanderthals, and why was it that modern humans alone survived? For the past seven years a team of international experts from a wide range of disciplines have worked together to provide a detailed study of the world occupied by the European Neanderthals between 60,000 and 25,000 years ago: the period known as Oxygen Isotope Stage 3. This... | |
 | Glaciation Of The Puget Sound Region (1913) by J. Harlen Bretz |
| Geohydrothermodynamics of a Water Planet, A New Geological Model, I: Quaternary Glaciation Theories, A Comprehensive and Critical Review of World Climatological Models by Carl Andrew Zapffe | |
| Pennsylvania glaciation, first phase;: Materials for a discussion of the attenuated border of the moraine described in volume Z of the second Geological survey of Pennsylvania, by Edward Higginson Williams |
| © 2008 BrightSurf.com |