Development of the Active Layer, Pingok Island, Alaska.

• Main Author: Fisher,Douglas M
• Other Authors: LOUISIANA STATE UNIV BATON ROUGE COASTAL STUDIES INST
• Format: Text
• Language: English
• Published: 1977
• Subjects: Snow; Ice and Permafrost; *FROST; *PERMAFROST; *TUNDRA; THICKNESS; SHAPE; ALASKA; TERRAIN; DEPTH; THAWING; VEGETATION; *Active layer(Frost); Pingok Island(Alaska); Arctic thaw; WUNR388002; Arctic; Ice; permafrost; Tundra; wedge*; Alaska
• Online Access: http://www.dtic.mil/docs/citations/ADA040913; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA040913

Depth-of-thaw measurements were made on Pingok Island, Alaska, throughout the 1972 thaw season. The research revealed that initial thaw is rapid and the rate decreases exponentially until a maximum depth is reached. Generally, the base of the active layer conforms to the surface configuration; however, local variations in the rate of thaw affect the shape and thickness of the active layer. An inversion of the surface topography often develops beneath hummocks that have a low vegetation cover and over ice wedges that are close to the surface. Slope exposure was found to be significant in affecting the thickness of the active layer, whereas moisture content and sediment size of the range discovered on Pingok Island have only minor effects on the depth of thaw. Thaw depths beneath a shallow pond were found to be greater than on the surrounding tundra. The dominant factor in influencing the thickness of the active layer in the study area is considered to be the presence of a vegetation cover. (Author)