Center of the orthographic projection is at latitude 30 degrees N., longitude 30 degrees. The north polar residual ice cap, which is cut by spiral-patterned troughs, is located at the top. The central part is characterized by a dark depression, Chryse basin, where several large outflow channels terminate. The lower-left corner is marked by a vast system of canyons, Valles Marineris, which extends eastward for several thousand kilometers.