Last updated: July 16, 2024
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NPS Geodiversity Atlas—San Antonio Missions National Historical Park, Texas
Geodiversity refers to the full variety of natural geologic (rocks, minerals, sediments, fossils, landforms, and physical processes) and soil resources and processes that occur in the park. A product of the Geologic Resources Inventory, the NPS Geodiversity Atlas delivers information in support of education, Geoconservation, and integrated management of living (biotic) and non-living (abiotic) components of the ecosystem.
Introduction
San Antonio Missions National Historical Park (SAAN) is located immediately south of downtown San Antonio along the upper San Antonio River basin in Bexar and Wilson Counties, southern Texas. Established on April 1, 1983, SAAN encompasses approximately 383 hectares (948 acres) and protects and preserves four 18th century Spanish Colonial Era mission complexes (Mission Concepción, Mission San José, Mission San Juan, Mission Espada), an extant mission ranch (Rancho de las Cabras), and associated historic structures (National Park Service 2016a). The historic missions of SAAN were once part of the Spanish Empire’s mission to colonize and evangelize Native Americans to Spanish-speaking Catholic citizens and represent one of the most complete and intact group of Spanish Colonial mission complexes in the world (National Park Service 2016d). Much larger than a normal church, the frontier missions of SAAN were large, self-sustaining settlement complexes featuring living quarters, workshops, storerooms, and their own irrigation and agricultural systems. The Mission Concepción and Mission Espada complexes are designated national historic landmarks and include the oldest unreconstructed stone church and the only functioning Spanish Colonial aqueduct in the United States, respectively. The extraordinary park resources of SAAN are internationally recognized, and the national historical park was designated a UNESCO World Heritage Site on July 15, 2015.
Geologic Setting
San Antonio Missions National Historical Park is situated in the Interior Coastal Plains subsection of the Coastal Plains physiographic province, a geologically young region comprised of Cenozoic-age strata dating back to the Paleocene Epoch (approximately 66 million years ago). The geology underlying the Spanish Colonial mission complexes of SAAN predominantly consists of Holocene fluviatile terrace deposits associated with the floodplain of the San Antonio River. Flanking the terrace deposits are older sedimentary rocks of the Eocene Midway Group and Wilcox Group, as well as calcareous silt, sand, and gravel of the Pleistocene Leona Formation. Exposures of the Midway Group and Wilcox Group are limited in SAAN, with known outcrops occurring along the San Antonio River near Espada Dam and beneath Espada Aqueduct where it traverses Sixmile Creek (Ewing 1996). The Rancho de las Cabras Unit of SAAN features Holocene terrace deposits in addition to greenish-brown glauconitic sand and clay deposits of the Eocene Weches Formation.
Regional Geology
San Antonio Missions National Historical Park is a part of the Coastal Plain Physiographic Province and shares its geologic history and some characteristic geologic formations with a region that extends well beyond park boundaries.
The Geologic Resources Inventory produces digital geologic maps and reports for more than 270 natural resource parks. The products listed below are currently available for this park, check back often for updates as many maps, reports, and posters are still in progress.
- Scoping summaries are records of scoping meetings where NPS staff and local geologists determined the park’s geologic mapping plan and what content should be included in the report.
- Digital geologic maps include files for viewing in GIS software, a guide to using the data, and a document with ancillary map information. Newer products also include data viewable in Google Earth and online map services.
- Reports use the maps to discuss the park’s setting and significance, notable geologic features and processes, geologic resource management issues, and geologic history.
- Posters are a static view of the GIS data in PDF format. Newer posters include aerial imagery or shaded relief and other park information. They are also included with the reports.
- Projects list basic information about the program and all products available for a park.
Source: Data Store Saved Search 3165. To search for additional information, visit the Data Store.
A NPS Soil Resources Inventory project has been completed for San Antonio Missions National Historical Park and can be found on the NPS Data Store.
Source: Data Store Saved Search 3116. To search for additional information, visit the Data Store.
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National Park Service Geodiversity Atlas
The servicewide Geodiversity Atlas provides information on geoheritage and geodiversity resources and values within the National Park System. This information supports science-based geoconservation and interpretation in the NPS, as well as STEM education in schools, museums, and field camps. The NPS Geologic Resources Division and many parks work with National and International geoconservation communities to ensure that NPS abiotic resources are managed using the highest standards and best practices available.