Regolith and Soil
Most landforms to some extent show the effects of weathering. On the bedrock surface of these landscapes are the accumulations of the products of weathering. Within these accumulations are materials displaying various degrees of physical, chemical, and biological alteration. These materials range in size from large boulders to clay sized particles less than 0.004 millimeters in diameter. Geomorphologists refer to these accumulations as regolith. Regolith can be further altered by climate, organisms, and topography over time to create soil. Soil is the most obvious landform of weathering.
Among the most interesting and most beautiful landforms of weathering are those which develop in regions of limestone bedrock. These landscapes are commonly called karst. In karst landscapes weathering is concentrated along joints and bedding planes of the limestone producing a number of different sculptured features from the effects of solution. Depressions of all sizes and shapes pit the landscape surface and are the most obvious features associated with karst. Beneath the surface, solution results in the formation of caves, springs, underground water channels, and deposits from evaporation.
Unique weathering landforms are also found in polar and sub-polar regions. In these regions, physical weathering processes are dominant, with active freeze-thaw and frost-shattering being the most active. Associated with these weathering processes are a number of unique surface features that develop only in periglacial environments. Collectively known as patterned ground, these surface features resemble circles, polygons, nets, steps, and stripes. The outlines of all of these features consist of elevated accumulations of coarse regolith fragments. Scientists believe that these outlines result from the systematic sorting of particles of a wide range of texture sizes by freeze-thaw action. The sorting causes larger fragments to move vertically upward and horizontally outward. Horizontal movement stops when one feature encounters another, linking the perimeter of two or more features. The linking of many adjacent features creates net-like patterns.