Adapted from the National Park Service Geodiversity Atlas, which draws on the Geologic Resources Inventory to describe the rocks, minerals, sediments, fossils, landforms, soils and geologic processes of each park.
The preserve
Big Thicket National Preserve is made up of nine separate land units and six water corridors just north of Beaumont, Texas, about 120 km (75 miles) from downtown Houston, spread across Hardin, Jasper, Jefferson, Liberty, Orange, Polk and Tyler Counties. Authorized on October 11, 1974, it covers about 44,147 hectares (109,092 acres) and was the first national preserve in the National Park System.
It protects what is left of "the Big Thicket," a biologically rich region of southeastern Texas where several major biomes meet: eastern hardwood forest, Gulf coastal plain, midwestern prairie and southwestern desert. The Big Thicket once covered more than 1.2 million hectares (3 million acres), but logging and oil production since the late 19th century have shrunk it to about 10% of that. The preserve's biodiversity is internationally recognized: it became a UNESCO Biosphere Reserve in 1981 and an American Bird Conservancy Globally Important Bird Area in 2001.
A landscape shaped by water
The preserve's landscape is dominated by a dynamic water system. At least 40% of it is wetland, with floodplains, oxbow lakes, sloughs, bogs and tributary streams. Its riparian areas support many birds, amphibians, reptiles and mammals, and they help prevent floods and improve water quality.
Image from the National Park Service's page.
The rocks beneath
Big Thicket lies in the Coastal Plain physiographic province of southeast Texas, which is underlain by a thick pile of hydrocarbon-rich strata dating back to the Triassic Period, about 250 million years ago. The rocks at the surface are far younger, all sedimentary layers from the Cenozoic Era:
| Age | Formations | Where |
|---|---|---|
| Miocene (23 to 5.3 million years ago) | Fleming Formation, the oldest bedrock in the preserve | upper reaches of the Neches River and Big Sandy Creek |
| Pleistocene | Willis Formation, Lissie Formation, Beaumont Alloformation, Deweyville Formation: gravel, sandstone, siltstone and mudstone laid down mainly by rivers and deltas | beneath much of the preserve |
| Holocene | loose surface deposits, the youngest mapped | floodplains and tributaries of the Neches River, Pine Island Bayou and Village Creek |
Part of the Geologic Resources Inventory's geologic map of the preserve. National Park Service.
Mapping the geology
The Park Service's Geologic Resources Inventory produces digital geologic maps and reports for more than 270 natural resource parks: scoping summaries recording how park staff and local geologists planned the mapping, GIS map data, reports on each park's geologic features, resource issues and history, and posters. Big Thicket also has a completed Soil Resources Inventory. Both are available through the NPS DataStore.
Sources
- National Park Service, "NPS Geodiversity Atlas—Big Thicket National Preserve, Texas." https://www.nps.gov/articles/nps-geodiversity-atlas-big-thicket-national-preserve-texas.htm
- Studies cited include Thornberry-Ehrlich (2018) and Chowdhury and Turco (2006); NPS DataStore saved searches 3411 (geology) and 3410 (soils): https://irma.nps.gov/DataStore/
In these publicationsBig Thicket National Preserve
Licence: CC0 1.0 (public domain) · Adapted from www.nps.gov
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