It ' s part of the Murray formation . The rover has already drilled and sampled lower examples of this basal unit to Mt Sharp . JPL have published reports on this formation stating that it was originally deposited as lakebed mud and then lithified turned to rock . The rover has already climbed approaching 100 meters since it first encountered this formation at the Pahrump hills , so that lake was around for a long time . This geological formation was buried under thousands of meters of overburden that almost filled Gale crater we can see the evidence of that filling on the mountain and the crater walls the fractures we see in these mudstone were formed after lithification , possibly a combination of pressure from the overburden and groundwater . JPL have stated that the light toned minerals we see in those fractures are a form of Gypsum , which were likely formed by precipitation from fluids high pressure groundwater circulating through those fractures . The presence of veins throughout the sandstone mudstone examined by Curiosity suggests that this process occurred well after sedimentation and cementationlithification of those sediments JPL release . In this particular weathered outcrop we can also observe horizontal mineral deposits that appear to follow the boundaries of sedimentary layers in the mudstone , this would indicate weakly cemented bonds between each layer in addition to the vertical fractures . As for the present appearance of this outcrop , it ' s shaped by millions of years of aeolian processes wind carved . The consensus of the reports I have studied favour that the whole of the crater was once filled with sedimentary rocks already stated above and has since been exhumed by aeolian processes , that exhumation continues until this present day . If I see any new reports on this region I ' ll post them here , but the science papers take time to be issued . They plan to drill at this site a larger outcrop in the days after the holiday weekend , so I look forward to seeing the results that we likely wont see until the middle of next year . Glad you are enjoying the mission thus far , the images speak a thousand words by themselves but a few added words can help tell the rover ' s story