News: Rounded Pebbles On Mars Indicate Past Flowing Water
Rounded pebbles discovered on Mars are giving scientists more evidence that water once flowed on the Red Planet. The pebbles were discovered by NASA’s newest rover Curiosity.
The rover is on a trek to the middle of the Gale Crater, where Mount Sharp protrudes three miles into the air. The rover snapped several pictures of areas that have densely packed pebbles.
The pebbles came in several different shapes and sizes, indicating that they traveled long distances in water, probably as part of an ancient riverbed. But the river dried up long ago on the now-desolate planet.
The Curiosity rover sent back several pictures of the rocks, which scientists divided into a photo mosaic. The area, called Hottah, was near the SUV-sized rover’s landing site near the north rim of Gale Crater. The small rocks ranged in size from 0.08 inches to 1.6 inches across.
In all, the researchers examined 515 pebbles, determining that all of their surfaces were round and smooth. While rocks worn by wind tend to be rough and angular, the rocks in the bottom of a riverbed are round and smooth. The appearance comes over time as the rocks get churned around with coarse sand.
The researchers explained that the cemented sections of rock on Mars were likely formed by a combination of fine sand, mud, gravel, and pebbles. The mixture hardened together, creating the formations seen by Curiosity. Over time, sand blowing on Mars also helped to make the rocks smooth.
Study co-author Dawn Summer, a geologist at the University of California, Davis, released a statement about the findings, explaining, "The main reason we chose Gale Crater as a landing site was to look at the layered rocks at the base of Mount Sharp, about five miles away."