evidence: Steep sided, relatively flat-topped isolated highland typically made up of horizontal sedimentary layers capped by a more resistant layer (lava or indurated crust) and surrounded by a debris apron. Plateaus, mesas, and buttes are flat on top and elevated above the surrounding terrain. Of the three, a plateau is the largest and a butte is the smallest (Figs. 1 and 2). A plateau can cover an area of hundreds of thousands of square kilometers. Mesas (M), buttes (B), and pinnacles (P) centered at 2.4°N 149°E in the volcanic Elysium Planitia NW of Zephyria Planum, made of the friable material of Medusae Fossae Formation. Notice that the caprock is densely cratered by small, eroded, pedestal craters. HiRISE ESP_028150_1825 (NASA/JPL/UA)