Weathering and Aluminum Interlayers in a Soil Catena: Hollis — Charlton — Sutton — Leicester1
- B. L. Sawhney2
Large amounts of a mineral with a stable 14Å. spacing are present in clay fractions of the Hollis-Charlton-Sutton-Leicester catena. When subjected to the usual procedures for the characterization of clay minerals, this mineral exhibited a behavior between that of vermiculite and chlorite. It was identified as vermiculite after interlayer aluminum was removed. Mild acid conditions and abundant illite and vermiculite in the parent micaceous schist are significant factors in forming these aluminum interlayers. The stability of aluminum interlayers both to sodium citrate and heat treatments increased with proximity to the surface. In Charlton fine sandy loam, 6 to 9 hours extraction with N sodium citrate were required to remove interlayers in the A1 horizon, whereas only 3 and 6 hours sufficed for the C and B22, respectively. The aluminum interlayers in well-developed and well-drained Charlton and Sutton soils are more stable to heat treatments than the material in poorly drained Leicester and shallow Hollis soils.
The cation-exchange capacity increased as much as 30 to 40% after the removal of aluminum interlayers; the increase was greater in more stable samples. Aluminum interlayers produced experimentally in vermiculite and montmorillonite resulted in stable 14Å. spacing and lowered the cation-exchange capacity of the original minerals considerably.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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