Chapter 6.3, Page 2 of 4

Hydrogeologic Units

The Eagle Basin developed in Middle Pennsylvanian time, concurrent with the uplift of the ancestral Rocky Mountains, and is generally regarded as a sub-basin of the Colorado trough. As such, the geology is dominated by carbonate rocks, near-shore sands, and evaporitic sequences. The primary Eagle Basin aquifers are found in the Permian and Pennsylvanian sandstones and the Mississippian and Devonian carbonates (Table 6.3-1). Identified sandstone aquifers include the Weber Sandstone and Maroon and Minturn Formations, which are underlain by the confining Eagle Valley Evaporite. The Mississippian and Devonian aquifers are composed of the Leadville Limestone, Gilman Sandstone, and Dyer Dolomite. Many of these units crop out along the edge of the Eagle Basin, which represents the regional recharge area. A generalized geologic cross-section of the basin outlines the structural relationships (Figure 6.3-3).

Table 6.3-1 Hydrogeologic Units of the Eagle Basin.

Modified from Geldon, 1986

Figure 6.3-3 Generalized geologic cross section through the Eagle Basin.
From Tweto, 1983.

Chapter 6.3, Page 2 of 4