Presidio mine, Shafter District, Presidio Co., Texas, USA
|Latitude & Longitude (WGS84):||29° 48' 46'' North , 104° 19' 44'' West|
|Latitude & Longitude (decimal):||29.81278,-104.32889|
|Köppen climate type:||BWh : Hot deserts climate|
|Other/historical region names associated with this locality:||Shafter|
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20 valid minerals.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
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66 - 145 Ma
|Mesozoic sedimentary rocks|
Age: Cretaceous (66 - 145 Ma)
Lithology: Sedimentary rocks
Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. 
100.5 - 145 Ma
Age: Early Cretaceous (100.5 - 145 Ma)
Stratigraphic Name: Presidio Formation
Comments: Conglomerate, limestone, sandstone, and siltstone. A basal well indurated pebble to boulder conglomerate, 30-80 ft thick grades upward to sandstone and siltstone, overlain by impure carbonate rocks, calcar sandst, and siltstone. Thickness about 400 ft+-. Ross (1943, p. 66) mapped five subdivisions, from base up, 1) 50-90 ft of soft marl, clay, thin-bedded sandy ls., calcar sandst. and shell breccia (missing locally), 2) 90-120 ft conglo., sandy ls., calcar. sandst., and a few beds of shale and marl. 3) 'tripartite unit' massive ls., calcar sandst., thinbedded ls., thin beds of shall breccia (Ostrea), 4) shell-breccia unit of 110-165 ft of soft sandst. interbedded with thin beds of sandy ls., hard clacar sandst., marl, shale, and shell breccias, 5) resistent unit of 25-50 ft of hard sandy to pure ls., with some beds of calcar. sandst. Total thickness 436 ft measured.
Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052.