This feature is an example of a class of volcanoes that are considerably smaller than the broad shield volcanoes. The summit consists of a single, very circular caldera with a smooth floor that predates the ejecta from two large impact craters. The lower flanks of the volcano, including portions of the impact craters, have been buried by the material that makes up the surrounding plains. This superpositional relationship indicates that the plains were emplaced subsequent to both the volcano and the large impact craters on the volcano. The plains are probably made up of lava supplied from Tharsis Montes that flowed down the sides of the broad uplift associated with the Tharsis shields. Both the plains and the volcano are cut by a graben, indicating tectonic activity subsequent to the emplacement of the plains.
This image is Copyright © by Calvin J. Hamilton. Any commercial/for-profit use of this image needs to be addressed to Calvin J. Hamilton. Caption by LPI.