ln the east the chalk is overlaid by sands and gravel which form the characteristic heathlands. On the seaward side of the Ridgeway are alternating clay and rock which contain many fossils.
The District is drained mainly by the River Frome which rises
at Evershot, just beyond the District boundary, traverses it from
west to east and empties into the sea at Poole Harbour.
A number of tributaries, such as the Cerne, Sydling Water, and the Puddle or Trent, flow down the north to south -valleys. These are typical chalk streams of crystal-clear water.