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october 2009

The trailblazers

Volcanologists have long been assessing the impacts of volcanic ash and gases on the environment and human health. This effort began in earnest when volcanologists at the U.S. Geological Survey undertook extensive studies of the environmental characteristics of ash from the 1980 Mount St. Helens eruptions. These studies included water leach tests showing that rain falling onto fresh ash can be quite acidic due to the liberation of acidic gas species that condense onto ash particles in the eruption cloud.

01 Oct 2009

Before Lucy: Older hominid Ardi challenges thinking about human evolution

Lucy, the 3.2-million-year-old Australopithecus afarensis fossil, has long been the poster child for early human evolution. But now she’ll have to share the spotlight with an even older hominid. After spending the last 15 years studying an ancient hominid species about the size of a chimpanzee, scientists revealed details about the 4.4-million-year-old Ardipithecus ramidus in a press conference today.

01 Oct 2009

It's all in the wrist: Humans lack a knuckle-walking ancestor

Though counterintuitive, scientists have turned their attention away from the feet and to the wrist and forearm to better understand how humans evolved upright walking, or bipedalism. African apes are humans’ closest living relatives, and because these apes knuckle-walk, some paleoanthropologists have suggested that African apes and humans share a knuckle-walking ancestor. A new study, however, reveals that lumping the locomotion of all African apes together is a mistake: Knuckle-walking may have evolved more than once in the ape lineage.

01 Oct 2009

Not the oldest hominid

At 4.4 million years old, Ardipithecus ramidus is not the oldest known hominid. In 2002, scientists announced they had discovered a hominid skull from the Sahel region of Chad. Named Sahelanthropus tchadensis, the species dates to about 7 million years ago. And a few years earlier, scientists had announced the discovery of several hominid fossils, including a thigh bone, in Kenya that dated to about 6 million years ago. They named the species Orrorin tugenensis.

01 Oct 2009

The vital statistics

Ardipithecus ramidus was a hominid that lived in Ethiopia’s Afar region 4.4 million years ago. After spending more than a decade studying the species, scientists can now provide a sketch of what the hominid looked like:

Brain: Ardipithecus had a brain size similar to that of a female chimpanzee, about 300 to 350 cubic centimeters.

Stature: Standing 120 centimeters tall and weighing 50 kilograms, Ardipithecus was about the size of a chimpanzee.

01 Oct 2009

Chemical clues reveal ancient geography

Reconstructing the history of supercontinents requires careful detective work. A variety of geological processes wipes the evidence clean, like a burglar who smears away his fingerprints. Yet even the most cautious criminals leave clues behind — and so do supercontinents.

07 Oct 2009

Venus' gentler, Earth-like past

Today, the surface of Venus is a hellhole, seared by scorching temperatures, crushing pressures and a toxic atmosphere of carbon dioxide with occasional clouds of sulfuric acid. But evidence is mounting that billions of years ago, Earth’s evil twin planet was a much more pleasant place — a second blue marble covered by water. The latest data come from the European Space Agency’s Venus Express spacecraft, which has spent three years constructing a detailed map of the surface of the planet’s southern hemisphere and finding new evidence for Earth-like plate tectonics and a watery past.

07 Oct 2009

Glaciers, not eruption: False alarm volcano mystery solved

When deep, long-period earthquakes started shaking the area around the Katla volcano on the southern tip of Iceland in 2001, officials feared it was a sign of an imminent eruption, as such quakes can be. So they were surprised when nothing happened. A new study identifies the source of the spurious signals: collapsing glaciers around the volcano, not the volcano itself. The finding may help researchers more accurately monitor other glacier-covered volcanoes.

07 Oct 2009

NASA's LCROSS crashes on the moon

Blogging on EARTH

Usually, NASA hopes its space probes land safely at their destinations. This morning, the agency was planning for a big explosion on the moon — all in the hopes of confirming the presence of water on our nearest neighbor.

09 Oct 2009

Geology 101: Reading the story in the rocks

David Harwood’s field geology course gives future teachers an introduction to several of geology’s most fundamental principles, including the stratigraphic basics described by Nicholas Steno in 1669. Go to the head of the class with this quick primer.

20 Oct 2009

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