Question

what are depressions in the context of a desert​

Answer 1

Answer:

Sand covers only about 20 percent of the Earth's deserts. Most of the sand is in sand sheets and sand seas--vast regions of undulating dunes resembling ocean waves "frozen" in an instant of time.

Nearly 50 percent of desert surfaces are plains where eolian deflation--removal of fine-grained material by the wind--has exposed loose gravels consisting predominantly of pebbles but with occasional cobbles.