The region is generally free from permafrost, but periglacial erosional processes are active because of the cold, wet climate. Streams are short and swift. Many enter the sea as waterfalls. In areas of porous volcanic rock, stream courses are widely spaced and are filled with water only during exceptionally heavy rains. Many small lakes occupy irregular ice-carved basins in rolling topography on the glaciated islands.
Lakes fill a few volcanic craters and calderas.
Soils Dominant soils are Typic Haplocryands and Typic Vitricryands. Most soils formed in deposits of volcanic ash or cinders over basaltic bedrock. Bare rock and rubble occur on volcanic cones, peaks, and high ridgetops. Volcanic material generally grades from coarse to fine with increasing distance from active volcanoes. Organic soils occupy depressions and some broad valley bottoms.