Frost polygons and mudboil-covered area
This image, scanned from a rather dirty 35 mm slide, shows contrasting patterned ground features on a low, flat terrain of poorly drained grass-sedge meadow and a relatively well-drained, slightly raised area formed on till and marine silty clay. The former terrain, though probably underlain by marine silty clay, also is ornamented by frost polygons because of the shallow (45–75 cm) depth of annual thaw in the peat, which keeps the underlying mineral sediments permanently frozen and rigid. The till/marine sediment terrain is ornamented, as is typical in this region, by mudboils and solifluction stripes (see image 0240 for a more complete explanation). This photo was taken from an altitude of 300-500 m. Frost wedges, such as those illustrated in images 0064, 0067, 0211, and 0212, probably extend downward from the frost cracks.
Updated 05/07/2010 AW