Nature and origin of layered deposits of the Martian polar regions

Layered deposits in the Martian polar regions are interpreted as accumulations of dust derived from atmospheric suspensions. Depressed and eroded terrains of the equatorial region are considered to be the principal sources of dust. A depositional model based on polar precipitation of dust predicts the formation of a vast, dome-shaped, featureless plateau underlain by layered deposits and occupying most of the area of annual frost cover. The rates of accumulation of dust and water ice in the polar regions have been estimated on the basis of atmospheric conditions in the present era. The analysis indicates an accumulation time of about 500 x 1 million years for the layered deposits and the presence of significant quantities of water ice in the deposits beneath the perennial cap.