Denver Basin

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The Denver Basin, sometimes also called the Denver-Julesberg Basin, or the D-J Basin, is a subterranean geologic formation located mostly in east-central Colorado in the United States. It underlies the Denver-Aurora Metropolitan Area on the eastern side of the Rocky Mountains.

The basin consists of a large syncline of stratified Mesozoic sedimentary rock layers, running north to south along the east side of the Front Range from the vicinity of Pueblo northward to Wyoming. The sag is deepest near Denver, where it reaches a depth of approximately 13,000 (3900 m) ft below the surface. The basin is strongly asymmetric: the Dakota-group sandstones outcrop in a "hog-back" ridge near Morrison a few miles west of Denver, reach their maximum depth beneath Denver, then ascend very gradually to their eastern outcrop in central Kansas.

According to current geologic theory, the basin starting forming as early as 300 million years ago, during the Colorado Orogeny that created the Ancestral Rockies. It was most likely further deepened in Tertiary time, between 65 and 45 million years ago, during the Laramide orogeny that created the modern Colorado Rockies. In particular, the uplifting of the Rockies in the Front Range caused the crust near Denver to buckle downward on the eastern side, deepening the basin. The basin later became filled with erosional sediment from the Rockies. The Front Range peaks rise approximately 22,000 ft (6600 m) from the floor of the basin under Denver.

The deep part of the basin near Denver became filled with Tertiary sandstone and conglomerate, a layer now called the Denver Formation. In the regions to the north and south of Denver, however, increased stream erosion wore away the uppermost layers of sandstone, revealing the parts of the underlying Cretaceous Pierre Shale to form wide valleys along the South Platte and Arkansas rivers known as the Colorado Piedmont.

The basin itself forms a petroleum province. Rocks in the basin, including various sandstones of the "Dakota" group, contain oil and gas. The Wattenberg Field is a large natural gas deposit north of Denver.

The upper formations of the Denver Basin are aquifers that serve as important sources of water supply in the region.