Soil Micromorphologic Features of Holocene Surface Weathering and a Possible Late Quaternary Buried Soil, Northwest Arkansas
Micromorphologic features of an alfisol developed in White River alluvium near Fayetteville, Arkansas are typical for this soil order. The A horizon has a relatively high organic matter content and an abundance of quartz sand grains with a silt and clay matrix. Voids are relatively common and some have been partly infilled. In contrast to the A horizon, the E horizon has less organic matter, larger voids, and some weak orientation of the clay matrix. The parent material for these horizons was deposited in the past 4,700 years and these pedologic horizons have formed since that time. In the underlying B horizon clay has accumulated in the form of grain coatings and caps and as void linings. Translocation of clay into this horizon has relatively decreased the abundance of matrix silt and clay, and the amount of void space. The clay matrix that remains has extensively become oriented and some of the void space that remains is planar in shape. Both these features are partly responsible for the subangular blocky structure of this horizon. Deposition of this parent material began more than 8,000 to 10,000 years ago and was complete by 4,700 years ago. Many of the soil features have formed since 4,700 BP as the soil surface accreted upward. The lower portion of the B horizon (2B) is developed in an older alluvial parent material, more than 10,000 years old. Some micromorphologic features suggest that the upper portion of this 2B horizon originally was an A/E horizon that has been modified after burial by subsequent weathering of the present ground soil. Some relict surface horizon features, such as relatively abundant voids, infilled vughs, and matrix, have persisted after burial. Other features characteristic of A horizons, such as organic matter, have been destroyed by oxidation. Many of the micromorphologic features in this 2B horizon have developed since burial, more than 10,000 years ago. Translocated clay features are abundant and partially mask the relict A/E horizon features. The lower part of the 2B horizon was a B horizon that continued to develop as a B horizon after burial. Translocated clay features are more abundant in this horizon than in the overlying relict A/E horizon.
Phillips, Diane and Guccione, Margaret J.
"Soil Micromorphologic Features of Holocene Surface Weathering and a Possible Late Quaternary Buried Soil, Northwest Arkansas,"
Journal of the Arkansas Academy of Science: Vol. 43, Article 18.
Available at: https://scholarworks.uark.edu/jaas/vol43/iss1/18