--- This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light-toned, layered, sedimentary rock outcrops in Becquerel Crater in the western Arabia Terra region. The crater may once have hosted a lake, into which these sediments were deposited. Although the fine, detailed layering in Becquerel was not known until the MGS MOC first began to image these materials in 1999, the presence of a grossly-layered, light-toned feature was known from Viking orbiter images and was speculated from those data to possibly represent evidence for the presence of a former lake. ---

http://www.msss.com/mars_images/moc/2006/01/14/ - Becquerel's Layers