5-727: The Chama Basin is a geologic structural basin located in northern New Mexico . The basin closely corresponds to the drainage basin of the Rio Chama and is located between the eastern margin of the San Juan Basin and the western margin of the Rio Grande Rift . Exposed in the basin is a thick and nearly level section of sedimentary rock of Permian to Cretaceous age, with some younger overlying volcanic rock . The basin has an area of about 3,144 square miles (8,140 km). In stratigraphic order (youngest to oldest),
10-462: A syncline fold. They are geological depressions , the inverse of domes . Elongated structural basins are a type of geological trough . Some structural basins are sedimentary basins , aggregations of sediment that filled up a depression or accumulated in an area; others were formed by tectonic events long after the sedimentary layers were deposited. Basins may appear on a geologic map as roughly circular or elliptical, with concentric layers. Because
15-520: A large number of specimens of the early theropod dinosaur Coelophysis bauri , was one of the most important of the basin. Even richer is the Snyder quarry, discovered in 1998. 36°38′N 106°41′W / 36.64°N 106.69°W / 36.64; -106.69 Structural basin A structural basin is a large-scale structural formation of rock strata formed by tectonic warping ( folding ) of previously flat-lying strata into
20-633: The stratigraphic units of the Chama Basin are: The basin is rich in fossil quarries. Its potential was first recognized by John Strong Newberry , who visited the basin in 1859 as part of the Macomb Expedition . Newberry visited the copper mines of El Cobre Canyon and identified Triassic plant leaves. The basin was subsequently visited by Edward Drinker Cope in 1874 during the Wheeler Survey , David Baldwin collected from sites in
25-608: The Arroyo del Agua area for five field seasons between 1877 and 1881, working first for O.C. Marsh and later for Cope, who was Marsh's bitter rival. The Baldwin bonebed yielded the first Permian vertebrates discovered in New Mexico. However, Baldwin failed to elicit much interest from either Marsh or Cope. The famous Whitaker quarry of Ghost Ranch , New Mexico, also been referred to as the Coelophysis quarry due to preserving
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