Clipmarks | Geology Clips

Impact Of Geology On The U.S. Civil War: War From The Ground Up

Tue, 07 Oct 2008 15:18:43 GMT

clipped by: Kelika
clipper's remarks: Whisonant and Ehlen also studied the terrain at Antietam, the site of the bloodiest battle in the Civil War, where on 17 September 1862 up to 23,100 soldiers were killed, wounded, or declared missing. "What's so striking at Antietam," says Whisonant, is that "two geologic units underlie [that area]. One is a very, very pure limestone that as it erodes it literally melts. Mostly what you get with that is a very even, level, open surface -- there just aren't a lot of deep holes and high hills that give soldiers a place to hide." On one area of this flat surface, known as Miller's Cornfield, "armies just shot each other to pieces until absolute exhaustion set in."

Clip Source: www.sciencedaily.com

Whisonant and Ehlen examined the geomorphology of several battlefields and compared the terrain to known casualties for each day of fighting. The question, says Whisonant, is whether a correlation exists between the geology of the battlefield and casualties taken there. For some battles in the Civil War, the story told by the shape of the land is clear: soldiers were at greater risk in some areas because the underlying geology created a more dangerous terrain.

"Gettysburg is a good example where the Union had the high ground, but one disadvantage was the hard rock that forms that high ground is so close to the surface that the soldiers couldn’t dig trenches." They were open targets for artillery assault by the Confederates. But the disadvantage didn’t just go one way: "Those Confederate soldiers had to go up an open slope formed on more erodible rock with nothing to get behind when they finally had to attack."

Tags: civil war, geology

Earliest animal footprints uncovered

Mon, 06 Oct 2008 15:58:08 GMT

clipped by: pokkets
clipper's remarks: Scientists didn't 'know' Pre-Cambrian life was well developed, they just seemed to reach their conclusions with too little evidence

Clip Source: www.abc.net.au

Scientists have found the oldest fossilised tracks of a tiny legged animal, providing further evidence that complex creatures existed on earth 570 million years ago.

The fossilised trails, thought to belong to a centipede or a leg-bearing worm that lived in the water, were found in sedimentary rocks in Nevada, says Ohio State University geology professor and the study chief author Loren Babcock.

The finding, presented to the Geological Society of America's meeting in Houston, shatters the belief that Pre-Cambrian life on earth was restricted to microbes and simple, multicellular organisms.

The tracks, two parallel rows of small dots, each about two millimetres in diameter, date back to the Ediacaran period - 630 to 542 million years ago.

They suggest that animals walked using legs at least 30 million years earlier than had been thought.

The Cambrian period (543 to 490 million years ago) saw an evolutionary explosion that produced most of the major animal groups we know today.

Accuracy of radiometric dating

Sun, 05 Oct 2008 00:06:31 GMT

clipped by: kroqben
clipper's remarks: an earlier clip got me looking for resources on the internet to explain simply, yet completely, the underpinnings of radiometric dating. www.pbs.org/evolution provides a good starting point for many such references. there is a religious tract on the internet that makes many claims about the inaccuracy of radiometric dating methods and the infallibility of the bible as a historical record. the link in this clip addresses some of its primary claims.

Clip Source: www.actionbioscience.org

The rejection of the validity of fossils and of dating by religious fundamentalists creates a problem for them:

The rejection of dating by religious fundamentalists is easier for them to make, but harder for them to demonstrate. The fossils occur in regular sequences time after time; radioactive decay happens, and repeated cross testing of radiometric dates confirms their validity.

Accuracy of dating

Dating in geology may be relative or absolute. Relative dating is done by observing fossils, as described above, and recording which fossil is younger, which is older. The discovery of means for absolute dating in the early 1900s was a huge advance. The methods are all based on radioactive decay:

A key point is that it is no longer necessary simply to accept one chemical determination of a rock’s age. Age estimates can be cross-tested by using different isotope pairs. Results from different techniques, often measured in rival labs, continually confirm each other.

caves

Sat, 04 Oct 2008 00:18:12 GMT

clipped by: patymurrieta

Clip Source: www.culture.gouv.fr

Various specialists in the field of geology participate in the research program during specific field seasons. In addition to studying the area immediately surrounding the cave, and more broadly, the Ardèche Valley, they are constructing a detailed geological map of the interior of the cavern. Some studies focus on geological phenomena and the processes of deposition and alteration that are responsible for the current nature of the cave. Other specialists are more specifically interested in the concretions, their age, constitution, and the micro-elements within them, which provide indications of the surface at different times. The courses of running water are also observed since they can explain displacements of bones, the differential preservation of paintings and deposits in different zones, the mechanisms of concretion formation, the zones in danger, etc. These specialists intervene in both the study of the cave and in developing measures for its conservation.

Earth's 'oldest rocks'

Sat, 27 Sep 2008 12:42:18 GMT

clipped by: fraynelson

Clip Source: news.bbc.co.uk

Earth's most ancient rocks, with an age of 4.28 billion years, have been found on the shore of Hudson Bay, Canada.

a team reports finding that a sample of Nuvvuagittuq greenstone is 250 million years older than any rocks known.

It may even hold evidence of activity by ancient life forms.

If so, it would be the earliest evidence of life on Earth - but co-author Don Francis cautioned that this had not been established.

"The rocks contain a very special chemical signature - one that can only be found in rocks which are very, very old," he said.

The professor of geology, who is based at McGill University in Montreal, added: "Nobody has found that signal any place else on the Earth."

"Originally, we thought the rocks were maybe 3.8 billion years old.

Ancient rocks act as a time capsule - offering chemical clues to help geologists solve longstanding riddles of how the Earth formed and how life arose on it.

Team finds Earth's 'oldest rocks'

Fri, 26 Sep 2008 16:01:31 GMT

clipped by: arifsali

Clip Source: news.bbc.co.uk

Earth's most ancient rocks, with an age of 4.28 billion years, have been found on the shore of Hudson Bay, Canada.

Writing in Science journal, a team reports finding that a sample of Nuvvuagittuq greenstone is 250 million years older than any rocks known.

It may even hold evidence of activity by ancient life forms.

If so, it would be the earliest evidence of life on Earth - but co-author Don Francis cautioned that this had not been established.

"The rocks contain a very special chemical signature - one that can only be found in rocks which are very, very old," he said.

The professor of geology, who is based at McGill University in Montreal, added: "Nobody has found that signal any place else on the Earth."

"Originally, we thought the rocks were maybe 3.8 billion years old.

"Now we have pushed the Earth's crust back by hundreds of millions of years. That's why everyone is so excited."

Tags: earth, discovery, rock

Rocks May Be Oldest on Earth, Scientists Say

Fri, 26 Sep 2008 15:58:32 GMT

clipped by: hitchhiker08

Clip Source: www.nytimes.com

Rocks May Be Oldest on Earth, Scientists Say

Some scientists say ancient bedrock found in Canada could turn out to be younger rock formed from much older remnants.

A swath of bedrock in northern Quebec may be the oldest known piece of the earth’s crust.

In an article appearing in Friday’s issue of the journal Science, scientists report that portions of that bedrock are 4.28 billion years old, formed when the earth was less than 300 million years old.

Other scientists are intrigued, but not yet entirely convinced that the rocks are quite that old.

“I hope that I’m wrong,” Dr. Mojzsis said. “If that happens, I believe there will be a land rush by geologists to northern Quebec.”

If the rocks are as old as claimed, the significance would be that “they’re not dramatically different from rocks you would find today in Japan or places like that,” Dr. Carlson said.

That suggests that the process of plate tectonics, reshaping and moving continents, could have already started on the very early earth.

Tags: quebec, geology, canada, oldest rocks

Brewster Kahle: digital library

Wed, 24 Sep 2008 18:33:55 GMT

clipped by: davidjclopes

Clip Source: www.ted.com

Brewster Kahle is an inventor, philanthropist and digital librarian. His Internet Archive offers 85 billion pieces of deep Web geology -- a fascinating look at the formation of the Internet over... Full bio and more links »

plate tectonics

Sun, 14 Sep 2008 16:52:23 GMT

clipped by: whooz

Clip Source: www.crystalinks.com

theory of geology that has been developed to explain the observed evidence for large scale motions

The lithosphere is cooler and more rigid, whilst the asthenosphere is hotter and mechanically weaker

Pacific Plate's Ring of Fire being most active and famous

oceanic lithospheres are denser than continental ones due to their greater mafic mineral content. As a result, the oceanic lithospheres generally lie below sea level (for example the entire Pacific Plate, which carries no continent), while the continental ones project above sea level

stress builds up in both plates and when it reaches a level that exceeds the slipping-point of rocks on either side of the transform-faults the accumulated potential energy is released as strain, or motion along the fault. The massive amounts of energy that are released are the cause of earthquake

zone. At the surface, the topographic expression is commonly an oceanic trench on the ocean side and a mountain range on the continental side.

Models reveal 'geology of Games'

Fri, 12 Sep 2008 14:37:52 GMT

clipped by: amgumen

Clip Source: news.bbc.co.uk

Different colours signify man-made layers, clay, gravel and sand

Decades of geological data are being used to produce 3D computer models of what lies beneath the proposed sites for the Glasgow Commonwealth Games.

The British Geological Survey (BGS) can draw on details gathered from 35,000 boreholes sunk in the city and records of old mine workings.

The BGS's Dr Diarmad Campbell said they would be a useful tool for guiding planning, development and where to sink new boreholes.

The model is very simple to use and can be turned around on the screen to view from any orientation and zoomed in on to see more detail

Is California on the Brink of Environmental Collapse?

Sat, 06 Sep 2008 15:30:19 GMT

clipped by: papananook
clipper's remarks: Water, water, water...when will we learn to respect it?

Clip Source: www.alternet.org

California has spared no expense to taxpayers or natural ecosystems to become the most hydrologically altered landmass on the planet.

There is no landmass on Earth quite like California. Here one finds the world's most ancient trees, bristlecone pines, more than 4,700 years old, in the White Mountains; the tallest and largest trees, the coast redwood and giant sequoia, respectively; the highest point in the lower 48 states, Mount Whitney; the lowest and hottest place in the Western Hemisphere, Death Valley; the largest western hemisphere estuary, the Bay Delta; an 800-mile coastline; the most irrigated acres; the most endangered species in the U.S.; the most diverse geology and biodiversity in the U.S.; and the greatest, most ecologically destructive water projects on Earth.

New clues on "The Great Dying"

Mon, 01 Sep 2008 02:55:48 GMT

clipped by: invictus
clipper's remarks:

The lessons of the Permian-Triassic massacre are "directly applicable to the present," said John Isbell, a geoscientist at the University of Wisconsin in Milwaukee. He said the world today is in danger of exceeding a CO2 "threshold" that could set off an environmental upheaval as great as the one 251 million years ago.

Clip Source: www.chron.com

An estimated 95 percent of all marine species and up to 85 percent of land creatures perished, according to Peter Ward, a paleobiologist at the University of Washington in Seattle.

Scientists call it "The Great Dying." Life took millions of years to recover.

Scientific sleuths, however, now think they're making progress toward pinning down what caused the extinction of most plants and animals on Earth some 251 million years ago.

The perpetrator wasn't an asteroid or comet, like the impact that wiped out the dinosaurs 65 million years ago and inspired movies such as Deep Impact and Armageddon.

Instead, it was a cascade of events that began with a monstrous outpouring of hot, reeking lava in Siberia. Repeated floods of lava released massive amounts of carbon dioxide, which produced a runaway greenhouse effect, oxygen-starved oceans and a poisoned atmosphere.

Tags: earth, mass extinction, carbon dioxide, greenhouse gases, atmosphere, geology, science

Opportunity on the road again :)

Sun, 31 Aug 2008 20:20:36 GMT

clipped by: mariana3

Clip Source: www.spaceweather.com

Mars rover Opportunity is leaving Victoria Crater, and it's exiting the way it came in. Put on your 3D glasses and behold the new tracks beside the old:

Graphic artist Patrick Vantuyne created the anaglyph by combining left- and right-eye images from Opportunity's navigation camera.

"Making stereo images of Mars has become almost routine for me, but it's still a thrill to see something new in 3D, which is hardly visible in a single picture," says Vantuyne. As an example, he notes the clouds in the upper-right corner of the anaglyph. Gaze for a while into the sky and watch the fluff emerge: full-size image.

Tags: mars, solarsystem, astronomy, geology, science, space

Volcanic sunsets

Sun, 31 Aug 2008 20:18:57 GMT

clipped by: mariana3

Clip Source: www.spaceweather.com

This weekend, observers around Europe are reporting the same "volcanic sunsets" widely observed last week in North America.

"This was probably due to aerosols in the stratosphere spewed by the August 7th eruption of the Kasatochi volcano in the Aleutian Islands."

Meanwhile, back in the USA, "the sky is on fire," reports Doug Zubenel of Kansas. "The colors tonight (Aug. 30th) were about as vivid as I have ever seen (photos)." One state away in Nebraska, Jerry Chab reports "the sky was white at the horizon and turned yellow, orange, red, purple, blue then finally black up high (photos). It was like a rainbow in clear skies!"

Tags: astronomy, climate, geology, volcano, sky, sunset

evolution: believe it or not.

Wed, 13 Aug 2008 21:22:09 GMT

clipped by: kroqben

Clip Source: talkorigins.org

Talk.origins is a Usenet newsgroup devoted to the discussion and debate of biological and physical origins. Most discussions in the newsgroup center on the creation/evolution controversy, but other topics of discussion include the origin of life, geology, biology, catastrophism, cosmology and theology.

The TalkOrigins Archive is a collection of articles and essays, most of which have appeared in talk.origins at one time or another. The primary reason for this archive's existence is to provide mainstream scientific responses to the many frequently asked questions (FAQs) that appear in the talk.origins newsgroup and the frequently rebutted assertions of those advocating intelligent design or other creationist pseudosciences.