Overview

The North Fork of Ninnescah River has eroded a broad shallow valley through sand and clay beds of the Tertiary Ogallala formation, which form the uplands. The valley lies in the lower part of the Permian "red beds" in the Ninnescah formation at the base of the Cimarron group. The "red beds" are underlain by shale, salt and anhydrite of the Wellington formation in the Big Blue group of the Permian series. The region is underlain by several thousand feet of marine sedimentaries. Soil and slopewash up to 15 feet thick blanket the sides of the valley. In places, alluvial terraces of gravelly sand up to 35 feet thick are present. Floodplain deposits of silty, clayey sand and gravelly sand range up to 40 feet thick. The upland on the right side of the valley is composed of sand and clay beds believed to constitute the lower part of the Ogallala formation. On the left side these beds are missing. The rock series, which forms the floor and sides of the reservoir basin, is composed principally of shale, the lower portion of which is gypsiferous. This shale series, about 100 feet thick, together with 20 feet of underlying shale, constitute parts of the Permian Ninnescah and Wellington formations. Beneath there are several thousand feet of sedimentaries including shale, limestone, salt and anhydrite. The Ninnescah shale formation, which crops out at a few places on the sides of the basin, appears to have regional dip at a slight angle to the southwest, modified in places by gentle monoclinal folds. No faulting is known. Jointing is common in the shale beds, probable a result of structural flexing.

General

Dimensions

Hydraulics & Hydrology