Show Alaska's Great Frost Depth The depth of permanently soil In n polar and regions is a subject subject sub sub- of perennial Interest concerning which few data are available In nu numerous numerous numerous nu- nu excavations made in placer mining In Alaska the ground Is permanently permanently per per- frozen to great depths beginning beginning beginning be be- ginning 18 Inches or 2 feet below the surface In the Klondike e according to the geological survey the alluvium Is froen frozen frozen fro- fro zen en to a depth of about feet At Fairbanks permanent ground frost has been found at many places to a depth of more than feet and the deepest deepest deep deep- deepest est shrift there penetrated feet of ot frozen alluvium In Seward peninsula many holes In permanently frozen alluvium alluvium al al- are ure more than 75 f fret feet et deep and andone andone andone one Is nearly feet deep On the other hand hantl some ground In Inthis Inthis inthis this region Is not frozen for reasons I not understood According to Dr A. A H. H Brooks when the moss Is stripped from the soil the he ground thaws and with open cut mining or cultivation the upper level of permanent ground frost seems gradually to descend It Is therefore believed that the ground frost is a survival of a climate colder than thun the present one and is preserved by the mat of moss and other vegetation Scientific vegetation Scientific American |