| Description |
The Soldier Summit quadrangle, Utah, comprises a 250-square- mile area in the central part of the state. It includes a part of the north east corner of the Wasatch Plateau and a part of the southwestern edge of the Uinta Basin. The pre-Quaternary stratigraphic section-about 12, 000 feet thick--consists of an upper Cretaceous and a lower Cenozoic non-marine sequence. The section to the north is representative of the Uinta Basin and it includes in ascending order the Colton, the Green River, and the Uinta Formations. The stratigraphic sequence to the south is representative of the Wasatch Plateau where two stratigraphic sections may be differentiated"" one in the east includes the following formations in ascending order: the Blackhawk, the Castlegate Sandstone, the Price River (restricted by removal of the Castlegate), the North Horn, and the Flagstaff; and the other in the west which is equivalent to the eastern section but it differs in that it contains a thick conglomerate unit between the Price River Formation and the North Horn Formation. This unit, here called the ""Bennion Creek Formation,"" reflects greater proximity to areas of mountain building. Prior to this work it had been believed that the Castlegate Sandstone and the Price River Formation (restricted) change westwards into a unit of conglomerate which in the northwestern Wasatch Plateau underlies the North Horn Formation. In the canyon of Bennion Creek in this area this conglomerate, the Bennion Creek Formation, is underlain disconformably by the Price River Formation (restricted) and the Castlegate Sandstone, and hence is not their facies equivalent. Structurally, the rocks are folded into a northeast-plunging anticline the Clear Creek anticline-which is flanked by the Beaver Creek syncline on the southeast, and the Tie Fork syncline on the northwest. The area is cut by a complex system of faults of which the Pleasant Valley and the Starvation Creek fault zones are the most important. A disconformity is recognized between the Price River Formation and the Bennion Creek Formation. In the area south of U.S. Highway 6-50 between Soldier Summit and Colton, Utah, secondary structures developed in the Flagstaff rocks by the gliding of the upper part of the formation under the influence of gravity. Geomorphically, the area is divided into several units: the Flagstaff Cuesta, Pleasant Valley Graben, Dry Valley Graben, Starvation Valley Graben, Dry Valley Horst Ridge, West Starvation Fault Scarp, South- east Starvation Ridge, Price River Canyon, Beaver Creek Canyon, Pond- town Creek and Fish Creek Canyons, Miller Canyon and Johnston Creek Canyon, and the Green River Hogbacks. Two main crustal movements have a positive record in the Soldier Summit quadrangle; these are the early Laramide orogeny, and the latest folding and normal faulting. The early Laramide orogeny is dated at the end of Price River time. The folding and normal faulting took place probably between the late Eocene and the Miocene. The area was a flood plain from Blackhawk time to the end of Bennion Creek time. Lacustrine conditions encroached over the area in North Horn time, and in Flagstaff time the area became part of the wide spread Flagstaff Lake. In Colton time, the area was again a flood plain with lacustrine conditions in the western part. Beginning with Green River time, the area became a part of Uinta Lake, and, except for the time of deposition of the fluviatile facies, the area continued to be part of that lake until its extinction probably in Duchesne River time. In post-Eocene time, the area was folded and faulted. Subsequent erosion produced the present drainage system and the geomorphic features of the quadrangle. |
