Sol 4333, April 1, 2016; Rover Field Report by Larry Crumpler, MER Science Team & New Mexico Museum of Natural History & Science: On this sol here on the west rim of Endeavour crater Opportunity has climbed west and up Marathon Valley in one of the final campaigns before moving on and beginning the summer field activities to the south southward. (…)
The latest drive on sol 4330 placed Opportunity on the edge of an area (shown with the red outline) where orbital remote sensing says there is an exposure of minerals that typically form when water alters rock. This is one of the reasons we came to Marathon Valley, so we want to do a good job of finding out where the minerals are, how they relate to the rocks they occur in, and what evidence there might be for how the alteration happened…. [More at link]