Steep and slippery slopes kept Curiosity from driving through Logan Pass and investigating a contact between two geologic units, but Curiosity found an alternate path. The rover took a slightly more southern route and is currently at Marias Pass (pronounced muh-RYE-ess) investigating the contact between the same two units. The bottom unit is similar to the rocks studied at the Pahrump Hills (the light-toned rocks at the very bottom of the large image) and the top unit is a bedded sandstone. The bedded sandstone contains larger, white grains in the matrix (some are circled in red, and you can see more images taken by MAHLI on Sol 998 here: http://mars.jpl.nasa.gov/msl/multimedia/raw/…). The sandstone also contains white veins similar to what Curiosity has seen in many other rocks during the mission. Mars is currently in solar conjunction, where the sun is between Earth and Mars. This occurs about every 26 months and disrupts communication between Earth and Curiosity (and all other missions on Mars). Curiosity will continue science operations after conjunction at the end of June.