May 30, 2013 — Detailed analysis and review have borne out researchers’ initial interpretation of pebble-containing slabs that NASA’s Mars rover Curiosity investigated last year: They are part of an ancient streambed.
The rocks are the first ever found on Mars that contain streambed gravels. The sizes and shapes of the gravels embedded in these conglomerate rocks — from the size of sand particles to the size of golf balls — enabled researchers to calculate the depth and speed of the water that once flowed at this location.
“We completed more rigorous quantification of the outcrops to characterize the size distribution and roundness of the pebbles and sand that make up these conglomerates,” said Rebecca Williams of the Planetary Science Institute, Tucson, Ariz., lead author of a report about them in the journal Science this week. “We ended up with a calculation in the same range as our initial estimate last fall. At a minimum, the stream was flowing at a speed equivalent to a walking pace — a meter, or three feet, per second — and it was ankle-deep to hip-deep.”
By Clay Dillow Posted 05.24.2013