NASA | JPL-Caltech | MSL Curiosity | 2017 Jan 17
[img3="The network of cracks in this Martian rock slab called "Old Soaker" may have formed from the drying of a mud layer more than 3 billion years ago. The view spans about 3 feet (90 centimeters) left-to-right and combines three images taken by the MAHLI camera on the arm of NASA's Curiosity Mars rover. Credit: NASA/JPL-Caltech/MSSS"]http://www.jpl.nasa.gov/spaceimages/ima ... _hires.jpg[/img3][hr][/hr]Scientists used NASA's Curiosity Mars rover in recent weeks to examine slabs of rock cross-hatched with shallow ridges that likely originated as cracks in drying mud. ...
If this interpretation holds up, these would be the first mud cracks -- technically called desiccation cracks -- confirmed by the Curiosity mission. They would be evidence that the ancient era when these sediments were deposited included some drying after wetter conditions. Curiosity has found evidence of ancient lakes in older, lower-lying rock layers and also in younger mudstone that is above Old Soaker. ...
The cracked layer formed more than 3 billion years ago and was subsequently buried by other layers of sediment, all becoming stratified rock. Later, wind erosion stripped away the layers above Old Soaker. Material that had filled the cracks resisted erosion better than the mudstone around it, so the pattern from the cracking now appears as raised ridges. ...
