ABSTRACT

The foothills of the Front Range west of Denver are experiencing rapid suburban growth. This area is underlain largely by Precambrian crystalline bedrock that is mantled by a discontinuous covering of surficial debris, regolith. The distribution and thickness of the regolith are of prime importance for determining the suitability of a given area for various landuses. This chapter describes a simple classification system and reconnaissance method for mapping the distribution of regolith and hard bedrock at and near the surface, and presents the information in a manner that can be easily understood and used by planners, developers, engineers, and landowners. The mapping is not intended for specific site evaluation, but rather for classification of areas of several acres or more for use in broad-scale landuse planning. Five map units are defined by the areal percentage of regolith more than 6 ft deep: alluvial soil, mostly soil, soil with subordinate rock, rock with subordinate soil, and mostly rock.