Clay Mineral Characterization of Modal Soil Profiles in Several Pennsylvania Counties
1963
Johnson, L. J. | Matelski, R. P. | Engle, C. F.
As part of the detailed soil survey of Pennsylvania, clay mineral types in modal soil profiles are being identified to determine: (1) weathering trends within profiles, (2) the distribution of clay types, and (3) the utility of clay mineral data for soil correlation. The clay mineral data is summarized on triangular diagrams which graphically illustrate the distribution of clay mineral types among horizons within a profile and between profiles of the same soil type. Differences in distribution of clay types between profiles of the same type are very common. The major change with increasing depth within the profiles studied is the increase in illite and the decrease in vermiculite and/or aluminum interlayered vermiculite. Kaolin minerals are relatively constant with increasing depth. Montmorillonite is generally associated with poor drainage and high organic matter content. It is concluded that soil correlation with clay mineral data is helpful but only of restricted application. Weathering is manifested by the sequence illite to vermiculite to aluminum interlayered vermiculite. Parent material controls the occurrence of kaolin and trioctahedral chlorite.
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