Roosevelt is on Mars (1) - Sol 727

This image mosaic from the MI aboard NASA's MER Opportunity shows detailed structure of a small fin-like structure dubbed "Roosevelt", which sticks out from the outcrop pavement at the edge of Erebus Crater.

Roosevelt lines a fracture in the local pavement and scientists hypothesize that it is a fracture fill, formed by water that percolated through the fracture. This would mean the feature is younger than surrounding rocks and, therefore, might provide evidence of water that was present some time after the formation of Meridiani Planum sedimentary rocks.

The image shows fine laminations (layers about 1 mm or 0,04" thick) that run parallel to the axis of the fin. Some of the textures visible in the image likely indicate that minerals precipitated from the outcrop rocks, but sediment grains are also apparent.

The frames combined into this mosaic were taken during Opportunity's 727th Sol (Feb. 8, 2006).