Shores and Islands 65 
Marine denudation is the process by which the sea erodes a 
shore line, breaks up the rocks and soil composing it, so that 
gradually the sea encroaches upon the land. The greatest 
destruction of shore jines occurs during storms when waves 
batter against rocks, tear heavy blocks of stone from cliffs, 
etc. The enormous destructive power of an ocean storm can 
be appreciated from the havoc wrought upon sea walls, from 
the washing away of lighthouses, from the easy way in which 
waves can move huge blocks of stone weighing many tons. 
1 q 
OF FSHORE————>\< SHORE OR BEACH ———————> 
'<——— FORESHORE———>«— BACKSHORE —> 
HIGH TIDE LEVEL 
Terms applied to beach profile. Berms are small impermanent terraces 
formed by deposition in calm weather and by erosion in storms. Plunge 
point is where waves break, depending on height of waves and tide. 
Coasts that are composed of hard rock exhibit a very ir- 
regular shore line: cliffs, pinnacles, natural arches, and rocky 
little islands jutting out into the ocean. Not uncommon is a 
region of shallow water or a level rock platform near the 
shore. 
Coasts composed of soft rock have a much more even and 
smooth appearance: broad sandy beaches, a gradual slope 
into the sea, and smaller size particles in the deposits. 
