Stream gravels have been derived from the Ouachita Mountains since at least Cretaceous times. Past studies have assigned ages to gravel deposits in the basins of the Saline and Little Missouri Rivers on the basis of altitude above local floodplains. This study examines the lithologies and textures of seven gravel outcrops ranging in age from Cretaceous to Quaternary to determine whether any patterns of variation based on assigned ages, variable sources, or precise depositional setting can be discerned. No variation patterns could be found for size distributions of sand-sized and larger fractions. However, the amount of silt-clay matrix decreases through time from a high of 24% in Cretaceous samples to 6% in Holocene materials. The ratio chert: sandstone (C:S) varies irregularly. Roundness and sphericity are lowin Cretaceous samples, and uniformly higher in later materials, though the highest mean roundness found was in a Cretaceous sample. Purple chert clasts occur only in Cretaceous samples, where the percentage of red chert is also higher. Most chert in Cenozoic deposits is brown. These differences are attributed to age and weathering. Those above depend on the source area and its distance from the depositional site.
"Textural and Lithologic Differences of Cretaceous, Tertiary, and Quaternary Gravels of South Arkansas,"
Journal of the Arkansas Academy of Science: Vol. 41
, Article 24.
Available at: http://scholarworks.uark.edu/jaas/vol41/iss1/24