 As this area of Britain was not subject to glaciation , the plateau remains as a remarkably old landform . Quartz and iron mineralisation can be detected in outcrops and subsoil . The underlying rocks are covered by moors are supported by wet , acid soil . The highest point on Exmoor is Dunkery Beacon ; at 519 metres ( 1 @,@ 703 ft ) it is also the highest point in Somerset . 
