Nili Fossae

Today's VIS image shows some of the linear depressions that comprise Nili Fossae. Nili Fossae is the name of a collection of curved faults and down-dropped blocks of crust between the faults. The "fossae," or graben, lie northeast of the large volcano Syrtis Major and northwest of the ancient impact basin Isidis Planitia. The troughs, which can be almost 500 meters (1,600 feet) deep , make concentric curves that follow the outline of Isidis Planitia. The graben likely formed as the crust sagged under the weight of lava flows filling the Isidis Planitia impact basin.