Strategies for Studying Saprolite and Saprolite Genesis
- Mark H. Stolt and
- James C. Baker
Saprolite is isovolumetrically weathered bedrock that retains the structure and fabric of the parent rock. This soil parent material forms in areas where crystalline rocks occur at or near the surface of the earth. Saprolite is generally overlain by 1 to 3 m of soil and commonly > 10 m thick. Although saprolite occurs worldwide and often comprises the majority of the regolith, relatively little research has focused on saprolite morphology and genesis. This chapter details various techniques for studying saprolite. Studies of saprolite are hindered by the significant depth of saprolite and the overlying soil, making the acquisition of samples for description and characterization difficult. Samples can be collected and descriptions made from highwalls in quarries. These can be augmented with samples collected with a drill rig, or a modified bucket auger system. A transition zone occurs between soil and saprolite. Identification of the transition zone boundary can be determined by examination of thin sections, and depth distributions of properties such as dithionite-citrate-bicarbonate (DCB) Fe, sand, and clay. Variability in saprolite properties and characteristics are considerable due to inherent differences within the structure, fabric, composition, and grain size of the parent rock, and commonly occurring shear zones and intrusions. Multiple samples within horizons can be used to estimate saprolite variability and better estimate a given parameter. Different systems are used by pedologists, geologists, and engineers to divide, describe, and classify residual regolith materials. Thus, a need exists for a classification system designed to meet the needs of each of the disciplines. Engineering properties of saprolite are considerably different from those of the overlying soil, suggesting that for engineering purposes soil and saprolite should be placed in separate classes. Investigations of saprolite genesis are used to estimate rates of saprolite formation, chemical denudation of the landscape, and isostatic uplift. Rates of saprolite formation, in conjunction with the thickness of saprolite on the landscape, can be used to estimate the maximum age of a landscape.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 1994. . Copyright © 1994 by the Soil Science Society of America, Inc., 5585 Guilford Rd., Madison, WI 53711 USA