Category Environment/Geology

This highly shocked zircon, from the Vredefort Dome in South Africa, shows thin, red bands that are a hallmark of meteorite impact. Photo: Aaron Cavosie

A study of zircons from a gigantic meteorite impact in South Africa casts doubt on the methods used to date lunar impacts. Durable crystals zircons are used to date some of the earliest and most dramatic cataclysms of the solar system. One is the super-duty collision that ejected material from Earth to form the moon roughly 50 million years after Earth formed. Another is the late heavy bombardment, a wave of impacts that may have created hellish surface conditions on the young Earth, about 4 billion years ago.

Both events are widely accepted but unproven, so geoscientists are eager for more details and better dates...

A topographic view of the South Pole-Aitken Basin. Reds are high; blues are low. Mafic Mound, (the reddish area in the center) stands 800 meters above the surrounding surface. Credit: NASA/Goddard/MIT/Brown

Within a giant impact basin near the moon’s south pole, there sits a large mound of mysterious origin. Research by geologists suggests the mound was formed by unique volcanic processes set in motion by the impact that formed the basin. The formation, known as Mafic Mound, stands about 800m tall and 75 km across, smack in the middle of a giant impact crater known as the South Pole-Aitken Basin. This new study suggests that the mound is the result of a unique kind of volcanic activity set in motion by the colossal impact that formed the basin.

“If the scenarios that we lay out for its for...

The Colorado River canyon, just above Grand Canyon (left), and Nanedi Vallis on Mars (right) pictured at the same scale shows how both canyons were formed by rivers that appear to have been approximately the same width. The river channel on Earth looks darker because it is filled with water, whereas Nanedi Vallis has been dry for billions of years. Credit: Sonny Harman/Penn State

The extensive valley networks on the surface of Mars were probably created by running water billions of years ago, but the source of that water is unknown. Now, researchers are using climate models to predict how greenhouse warming could be the source of the water.

“Everyone is looking for life on Mars, and if Mars was habitable early on as indicated by flowing water, then the chances of there being some sort of l...

The rod-shaped bacterium E. coli served as the model system for DNA repair in the study. | Photo by U.S. Department of Defense

Bacterium exhibits remarkable ability to repair or prevent DNA damage arising from internal processes, contrary to previous findings. A study led by Indiana University biologist Patricia Foster and colleagues has found that forces in the external environment and oxidation are the greatest threats to an organism’s ability to repair damage to its own DNA.

The results are based on the first comprehensive, whole genome analysis of spontaneous mutation in Escherichia coli
“Our study investigated 11 DNA repair pathways previously identified as resulting in spontaneous mutations,” said Prof Foster...