Genesis of Cambic and Argillic Horizons in Two Northern Utah Aridisols1
- R. J. Southard and
- A. R. Southard2
A study of the mineralogy and morphology of two northern Utah Aridisols (Camborthid and Haplargid) formed from ancient Lake Bonneville sediments revealed small but important differences between the two soils in the degree of weathering and soil development. The B horizons of both pedons meet the argillic horizon textural requirement. An incipient argillic horizon was identified in the Haplargid on the basis of thin, discontinuous pore argillans observed with a scanning electron microscope. The Camborthid Bw horizon is a cambic horizon, as indicated by partial removal of carbonates, development of structure, and lack of illuviation argillans. The Camborthid is calcareous throughout, and interlayering of mica-smectite in the clay fractions is extensive. Stronger weathering in the Haplargid is inferred from the nearly complete removal of carbonates from surface horizons and more complete alteration of mica to smectite (i.e., less interlayering). The argillic horizon has formed in about 9000 yr under the influence of at least two pluvial periods. The cambic horizon formed in an environment at least as dry as at present, and it is still calcareous after about 6000 yr. The scanning electron microscope is a valuable tool for inferring soil-forming processes from soil fabric morphology, especially in weakly-developed horizons.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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