Curiosity investigated a spot called Altar Mountain at the Darwin waypoint on sol 394. This MAHLI image, taken of a mostly shadowed spot on the outcrop, shows that Bardin Bluffs is a poorly sorted pebble conglomerate. Most of the grains are subangular, with gravel measuring 4 to 10 millimeters across. The poor sorting and disorganization suggests it was deposited rapidly.
The description is paraphrased from a talk given by Aileen Yingst to the 2014 Lunar and Planetary Science Conference.
This is a MAHLI focus merge product; it was made on the rover's sol 396 from data acquired on sol 394.