Mountain:  high land mass projecting conspicuously above its surroundings and usually of limited width at its summit.     Valleys:  a long depression in the land surface, usually containing a river, formed by erosion or by movements in the earth's crust.    Plateau:  elevated, level or nearly level portion of the earth's surface, larger in summit area than a mountain andbounded on at least one side by steep slopes, occurring on land or in oceans.   Plains:    a  broad level expanse, as a part of the sea floor or a lunar mare.   Glacier:  a slowly moving mass of ice originating from an accumulation of snow. It can either spread outfrom a central massor descend from a high valley.   Stream:  A flow of water in a channel or bed, as a brook, rivulet, or small river   Delta: a  usually triangular alluvial deposit at the mouth of a river.   Estuary: t he part of the wide lower course of a river where its current is met by the tides.   Gulfs:  a large ...