Antarctic research helps shed light on climate change on MarsAugust 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 |
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| Related Glaciation Current Events and Glaciation News Articles California's Ancient Kelp Forest The kelp forests off southern California are considered to be some of the most diverse and productive ecosystems on the planet, yet a new study indicates that today's kelp beds are less extensive and lush than those in the recent past. Snail fossils suggest semiarid eastern Canary Islands were wetter 50,000 years ago Fossil land snail shells found in ancient soils on the subtropical eastern Canary Islands show that the Spanish archipelago off the northwest coast of Africa has become progressively drier over the past 50,000 years. Volcanoes played pivotal role in ancient ice age, mass extinction Researchers here have discovered the pivotal role that volcanoes played in a deadly ice age 450 million years ago. Perhaps ironically, these volcanoes first caused global warming -- by releasing massive amounts of carbon dioxide into the atmosphere. When they stopped erupting, Earth's climate was thrown off balance, and the ice age began. Egg-shaped legacy of Britain's mobile ice-sheet The ice sheets that sculpted the landscape of northern Britain moved in unexpected ways and left distinctive egg-shaped features according to new research. University of Leicester geologists demonstrate extent of ancient ice age Geologists at the University of Leicester have shown that an ancient Ice Age, once regarded as a brief 'blip', in fact lasted for 30 million years. Prehistoric global cooling caused by CO2, research finds Ice in Antarctica suddenly appeared - in geologic terms - about 35 million years ago. For the previous 100 million years the continent had been essentially ice-free. Study: Did early climate impact divert a new glacial age? The common wisdom is that the invention of the steam engine and the advent of the coal-fueled industrial age marked the beginning of human influence on global climate. Why 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. More Glaciation Current Events and Glaciation News Articles |
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