Examination of surface sections along the Colorado Front Range from Walden to Beulah, Colorado, reveals that five sandstone units in the

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upper Morrison Formation (Upper Jurassic) and lower Dakota Group (Lower Cretaceous) may offer potential zones for exploration in the central Denver basin.

The upper portion of the Morrison contains sandstones of both straight and laterally accreting channel fill. The Lytle Sandstone of the Dakota Group is characterized by a trough-bedded, pebble conglomerate deposited in an extensive network of multiple, laterally equivalent channels. This system was replaced by the finer grained Dutch Creek Sandstone (new term), which was deposited in a high-sinuosity meander belt that produced widely spaced sand bodies characterized by flat beds and white clay chips. A period of transgression then followed with the deposits from this event being represented by the sandstones and burrowed siltstones of the Massey Draw Sandstone (new term). The overlying Plainview Sandstone was deposited in a regressive setting and thickens into occasional channel depos ts that contain log fragments, carbonaceous debris, and trough-bedded sandstones. The channel grade laterally into slightly burrowed siltstones and fine-grained sandstones that increase upward in grain size and flow regime.

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