Posts tagged geology

Ancient Forest Thaws From Melting Glacial Tomb

An ancient forest has thawed from under a melting glacier in Alaska and is now exposed to the world for the first time in more than 1,000 years.

Stumps and logs have been popping out from under southern Alaska’s Mendenhall Glacier — a 36.8-square-mile (95.3 square kilometers) river of ice flowing into a lake near Juneau — for nearly the past 50 years. However, just within the past year or so, researchers based at the University of Alaska Southeast in Juneau have noticed considerably more trees popping up, many in their original upright position and some still bearing roots and even a bit of bark, the Juneau Empire first reported last week.

"There are a lot of them, and being in a growth position is exciting because we can see the outermost part of the tree and count back to see how old the tree was," Cathy Connor, a geology professor at the University of Alaska Southeast who was involved in the investigation, told LiveScience’s OurAmazingPlanet. "Mostly, people find chunks of wood helter-skelter, but to see these intact upright is kind of cool."

The team has tentatively identified the trees as either spruce or hemlock, based on the diameter of the trunks and because these are the types of trees growing in the region today, Connor said, but the researchers still need to further assess the samples to verify the tree type.

A protective tomb of gravel likely encased the trees more than 1,000 years ago, when the glacier was advancing, Connor said, basing the date on radiocarbon ages of the newly revealed wood. As glaciers advance, Connor explained, they often emit summer meltwater streams that spew aprons of gravel beyond the glacier’s edge.

[Full Story]

(Source: scinerds)

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Super-Eruption Launched Algae Army Into the Sky

Slimy brown algae not only survived a wild ride into the stratosphere via a volcanic ash cloud, they landed on distant islands looking flawless, a new study finds.

"There’s a crazy contrast between these delicate, glass-shelled organisms and one of the most powerful eruptions in Earth’s history," said lead study author Alexa Van Eaton, a postdoctoral scholar at both the Cascades Volcano Observatory in Washington and Arizona State University.

The diatoms were launched by the Taupo super-eruption on New Zealand’s North Island 25,000 years ago. More than 600 million cubic meters (20 billion cubic feet) of diatoms from a lake flew into the air, Van Eaton reported Sept. 6 in the journal Geology. Lumped together, the microscopic cells speckled throughout Taupo’s ash layers would make a pile as big as Hawaii’s famed Diamond Head volcanic cone.

Super-Eruption Launched Algae Army Into the Sky

Slimy brown algae not only survived a wild ride into the stratosphere via a volcanic ash cloud, they landed on distant islands looking flawless, a new study finds.

"There’s a crazy contrast between these delicate, glass-shelled organisms and one of the most powerful eruptions in Earth’s history," said lead study author Alexa Van Eaton, a postdoctoral scholar at both the Cascades Volcano Observatory in Washington and Arizona State University.

The diatoms were launched by the Taupo super-eruption on New Zealand’s North Island 25,000 years ago. More than 600 million cubic meters (20 billion cubic feet) of diatoms from a lake flew into the air, Van Eaton reported Sept. 6 in the journal Geology. Lumped together, the microscopic cells speckled throughout Taupo’s ash layers would make a pile as big as Hawaii’s famed Diamond Head volcanic cone.

(Source: scinerds)

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High cliffs surrounding Echus Chasma on Mars

What created this great cliff on Mars? Did giant waterfalls once plummet through its grooves? With a four-kilometer drop, this high cliff surrounding Echus Chasma, near an impressive impact crater, was carved by either water or lava. A leading hypothesis is that Echus Chasma, at 100-kilometers long and 10-kilometers wide, was once one of the largest water sources on Mars. If true, water once held in Echus Chasma likely ran over the Martian surface to carve the impressive Kasei Valles, which extends over 3,000 kilometers to the north. Even if initially carved by water, lava appears to have later flowed in the valley, leaving an extraordinarily smooth floor. Echus Chasma lies north of tremendous Valles Marineris, the largest canyon in the Solar System. The above image was taken by the robotic Mars Express spacecraft currently orbiting Mars.

Image credit: G. Neukum (FU Berlin) et al., Mars Express, DLR, ESA

via distant-traveller:

sagansense:

High cliffs surrounding Echus Chasma on Mars

What created this great cliff on Mars? Did giant waterfalls once plummet through its grooves? With a four-kilometer drop, this high cliff surrounding Echus Chasma, near an impressive impact crater, was carved by either water or lava. A leading hypothesis is that Echus Chasma, at 100-kilometers long and 10-kilometers wide, was once one of the largest water sources on Mars. If true, water once held in Echus Chasma likely ran over the Martian surface to carve the impressive Kasei Valles, which extends over 3,000 kilometers to the north. Even if initially carved by water, lava appears to have later flowed in the valley, leaving an extraordinarily smooth floor. Echus Chasma lies north of tremendous Valles Marineris, the largest canyon in the Solar System. The above image was taken by the robotic Mars Express spacecraft currently orbiting Mars.

Image credit: G. Neukum (FU Berlin) et al., Mars Express, DLR, ESA

via distant-traveller:

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Dirty thunderstorms

A dirty thunderstorm (also, Volcanic lightning) is a weather phenomenon that occurs when lightning is produced in a volcanic plume. A study in the journal Science indicated that electrical charges are generated when rock fragments, ash, and ice particles in a volcanic plume collide and produce static charges, just as ice particles collide in regular thunderstorms.

(Source: spaceplasma, via rednightmare18-deactivated20140)

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First X-ray view of Martian soil
This graphic shows results of the first analysis of Martian soil by the Chemistry and Mineralogy (CheMin) experiment on NASA’s Curiosity rover. The image reveals the presence of crystalline feldspar, pyroxenes and olivine mixed with some amorphous (non-crystalline) material. The soil sample, taken from a wind-blown deposit within Gale Crater, where the rover landed, is similar to volcanic soils in Hawaii.
Curiosity scooped the soil on Oct. 15, 2012, the 69th sol, or Martian day, of operations. It was delivered to CheMin for X-ray diffraction analysis on October 17, 2012, the 71st sol. By directing an X-ray beam at a sample and recording how X-rays are scattered by the sample at an atomic level, the instrument can definitively identify and quantify minerals on Mars for the first time. Each mineral has a unique pattern of rings, or “fingerprint,” revealing its presence. The colors in the graphic represent the intensity of the X-rays, with red being the most intense.
Image credit: NASA/JPL-Caltech/Ames

First X-ray view of Martian soil

This graphic shows results of the first analysis of Martian soil by the Chemistry and Mineralogy (CheMin) experiment on NASA’s Curiosity rover. The image reveals the presence of crystalline feldspar, pyroxenes and olivine mixed with some amorphous (non-crystalline) material. The soil sample, taken from a wind-blown deposit within Gale Crater, where the rover landed, is similar to volcanic soils in Hawaii.

Curiosity scooped the soil on Oct. 15, 2012, the 69th sol, or Martian day, of operations. It was delivered to CheMin for X-ray diffraction analysis on October 17, 2012, the 71st sol. By directing an X-ray beam at a sample and recording how X-rays are scattered by the sample at an atomic level, the instrument can definitively identify and quantify minerals on Mars for the first time. Each mineral has a unique pattern of rings, or “fingerprint,” revealing its presence. The colors in the graphic represent the intensity of the X-rays, with red being the most intense.

Image credit: NASA/JPL-Caltech/Ames

(Source: distant-traveller, via holospace)

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Iceland Seen From the Air by Axel Sigurðarson

(Source: expose-the-light, via scinerds)

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Patterns in Nature: Rocks and Lava

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The iridium layer, or K/T Boundary

The thin, grey claystone layer contains 1,000 times more iridium (REE) than the layers above and below, along with shocked quartz.  Iridium is extremely rare on Earth, but a very common/abundant element in asteroids.  This layer has been identified in 100+ places around the Earth.

This boundary marks the extinction of the non-avian dinosaurs.

(Source: elegantbuffalo)

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 Yellowstone Supervolcano Eruptions More Frequent Than Thought? They may also be weaker—but could still affect much of the U.S.

Richard A. Lovett

for National Geographic News

Published May 1, 2012

The supervolcano underlying much of Yellowstone National Park and beyond may erupt more frequently than thought, a new study says.

What’s more, Yellowstone’s “super eruptions” may be slightly less super than suspected—but still strong enough to destroy all of Yellowstone and more, researchers say.

Much of Yellowstone National Park—which covers parts of Idaho, Montana, and Wyoming—lies in a roughly 40-mile-wide (70-kilometer-wide) crater formed by the collapse of a massive volcanic cone during the area’s most recent super-eruption, some 640,000 years ago.

Before then, Yellowstone had seen two other super-eruptions: one about a million years ago and another about two million years ago. Now, however, it seems the earliest blast might actually have been two cataclysmic explosions, thousands of years apart.

(Related: "Yellowstone Has Bulged as Magma Pocket Swells.")

Double Blast

Among geologists, it’s no secret that the two-million-year-old Yellowstone lava deposit has three layers.

"That got us thinking whether these things were representing different magma batches [from a single eruption] or different events," study leader Ben Ellis, a volcanologist and postdoctoral researcher at Washington State University, told National Geographic News.

Ellis’s team examined rock samples from all three layers using the latest isotope dating techniques, which rely on the known rates of decay of certain elements to date objects.

It turns out that the uppermost layer of the roughly two-million-year-old lava deposit—about 12 percent—was laid down about 6,000 years later than the other two layers, according to the study.

This suggests that the supervolcano’s active periods may span thousands of years and feature multiple massive eruptions—that “explosive volcanism from Yellowstone is more frequent than previously thought,” Ellis said in a statement.

The findings also raise the question of whether the other two layers represent separate eruptions, currently an unsolvable mystery, since even the latest dating techniques have relatively wide margins of error.

"Right now plus or minus 4,000 years is about as good as we can do [when dating] rocks of this age," Ellis said.

(Find out what’s really going on under Yellowstone and how the next super-eruption could unfold in "When Yellowstone Explodes" [National Geographic magazine, August 2009].)

Supervolcano Eruption Still “Definitely Big”

Though the team’s findings split that first Yellowstone super-eruption into two smaller blasts, Ellis points out that even the second, smaller eruption would have been an explosion for the ages.

"We just recognized an eruption 300 times the size of Mount St. Helens’," said Ellis, referring to the Washington State volcano’s 1980 eruption. (See pictures of Mount St. Helens before and after the blast.)

The larger of the two proposed blasts would still rank as the fourth largest eruption known to science. “It’s definitely big,” Ellis said. “We’re not taking that away.”

If something like that eruption were to happen today, he added, all of Yellowstone National Park would probably be devastated. What’s more, “the ashfall would likely be all over the continental U.S.,” he said.

Ellis refused to speculate about when such an eruption might occur again, but one thing’s for sure: Yellowstone—rising on a bulging magma pocket, seething with volcanically heated geysers and hot springs—is still very much alive.

The new Yellowstone-supervolcano study will appear in the June issue of the journal Quaternary Geochronology.

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