Lake Kemp
| City of Wichita Falls | |
|---|---|
| Coordinates: 33°53′49″N 98°30′54″W / 33.89694°N 98.51500°WCoordinates: 33°53′49″N 98°30′54″W / 33.89694°N 98.51500°W | |
| Country |
 United States
|
| State |
 Texas
|
| County | Wichita |
| Area | |
| • Total | 183.1 km2 (70.1 sq mi) |
| • Land | 183.0 km2 (70.66 sq mi) |
| • Water | 0.1 km2 (0.04 sq mi) |
| Elevation | 289 m (948 ft) |
The exposed strata at the surface in and around Wichita Falls are the products of one ancient period of deposition with a modest amount of recent and modern alteration. In all cases, the strata are products of terrigenous (non-marine) environments dominated by fluvial depositional and erosional systems (rivers and streams).
The rocks found in and around Wichita Falls result from southwesterly-flowing Permian streams that deposited sands in channels and silts and clays on the surrounding floodplains. Calcium-carbonate rich soils concurrently developed adjacent to these streams. These were likely buried by further Permian sedimentation and then lithified. erosion removed the younger rocks, exposing the current strata. Exposures of sediments indicate that northeast-flowing streams locally deposited silts, clays, sands, and some gravels on the Permian rocks. These are subsequently modified by modern (Holocene) stream erosion and deposition.
In the Permian geologic period, North-Central Texas was a part of the western coastal zone of equatorial Pangea, a super-continental land mass. Nearby uplifts and mountainous regions, such as the Muenster Arch and Red River Uplift, the Wichita, Arubckle, and Ouachita mountains developed by the end of the Pennsylvanian, providing elevated topography to the north and east during the Permian. The rocks of the Permian Basin of West Texas record a contemporaneous shallow inland sea. The resulting topography provided northeast-to-southwest gradients for stream flow and sediment movement. The sediments deposited by the Permian streams of North-Central Texas were likely reworked clastic materials from Middle Pennsylvanian stream and fan-delta sediments proximal to the Ouachita foldbelt and Muenster Highlands.
The Petrolia Formation (of the Late Wolfcampian-Leonardian systems) dominates the exposed Permian strata in Wichita falls, as mapped by the 1987 Texas Atlas of Geology. The map describes the formation as 360–400 feet of weakly or unstratified mudstone with laminated, cross-bedded sandstone lenses. The formation increases in mudstone content upsection. Sandstone lenses contain terrestrial fossils of plants, vertebrates, and footprints. The unit contains calcareous nodules of varying sizes as well as poorly indurated "conglomerate" with vertebrate fossils. In general the entire package is only weakly lithified, perhaps indicating that the region was not appreciably covered by a thick package of younger strata.
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Wikipedia