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29 <br />progressively decreases in the younger formations as they outcrop <br />at greater distances from the mountain front. Between Lyons and <br />the northern Colorado border a series of Northwest-tending high- <br />angle bedrock faults offset the sedimentary beds. Draping of <br />sediments over these faults produces a series of en-echelon folds <br />and faults. Taken together, these intermediate-scale structure <br />deformations, regional deformations produced by the Front Range <br />and the Denver Basin, and more localized small-scale folding and <br />faulting, result in a generally complex geologic setting <br />throughout the Foothills Belt. <br />A maximum of approximately 12,700 feet of sediment is found in <br />the vicinity of Dowe Flats. Only those formations beneath the <br />lower Pierre Shale are present. In general, the geologic section <br />is composed of alternating sandstone and shale layers and some <br />limestones. Beginning at the bottom of the section and working <br />upward in both depth and time, the individual units display a <br />variety of depositional origins. <br />All of these sedimentary units are Upper Cretaceous in age. The <br />synclinal structure of the central Dowe Flats basin is such that <br />the youngest (Pierre Shale) formation is exposed over much of the <br />eastern portion of the valley bottom with the older strata <br />forming concentric horseshoe like rings as they outcrop around <br />the valley perimeter on the east and west margins. <br />Structurally the region surrounding Dowe Flats is extremely <br />complex with both intense and sometimes superimposed folding as <br />well as Post-Cretaceous faulting. In this context, the <br />simplicity of the central interior portion of Dowe Flats is <br />almost anomalous. Interpretation of available information does <br />not indicate the presence of major faulting, shearing, or <br />significant folding in the interior portion of Dowe Flats. <br />The important formations in this area are all upper Cretaceous in <br />age and are limited to the middle of the regional stratigraphic <br />column. They include the Dakota Group, the Ft. Benton Formation, <br />the Niobrara Formation and the Pierre Shale. The general <br />