GEOG 120 Lecture 19: GEOG 120-03:20:14.pdf
Document Summary
Near a glaciated region. High latitude or high altitude. 25% of the land surface is periglacial. Active layer freezing and thawing conditions, water can permeate, approx 15- 20cm thick. Permafrost table is the upper surface of the permafrost. Frozen ground, can extend to 1 km in depth of frozen ground. Types of permafrost: continuous, discontinuous (most of the ground is permanently frozen), alpine. Freezing and thawing of water. Water expands by 9% when freezing, and can crack or break rock features. Rock debris produced is angular. Continental ice sheets grow and spread. Shrink during a warming trend. Several theories have been proposed. Change in the position of the continents. Decrease in the sun"s energy. Variations in the earth"s orbit.
