Geology and Stratigraphy of the Chihuahuan Desert Network Parks
The Chihuahuan Desert Inventory & Monitoring Network consists of seven national park units in the desert and mountain landscapes of southeastern New Mexico and west Texas. The Chihuahuan Desert is an expansive ecoregion covering nearly 647,500 km2 (250,000 mi2 ) of the southwestern United States and northern Mexico and represents one of the most biologically diverse deserts in the Western Hemisphere. The Chihuahuan Desert is geographically isolated and distinct ecologically from adjacent arid desert regions by two mountain ranges, the Sierra Madre Occidental to the west and the Sierra Madre Oriental to the east. Within the United States, the Chihuahuan Desert spans the Trans-Pecos region of Texas, along the Rio Grande River, into southern New Mexico.
The Chihuahuan Desert consists of a basin and range topography with broad desert valleys bordered by fault-block mountains. The topography forms closed basins which support playa lakes and dune field development. This ecoregion lies within the Pecos and Rio Grande drainage systems in the U.S. The Permian or Capitan reef system is represented in the Guadalupe and Glass Mountains in southern New Mexico and west Texas, supporting extensive cave and karst resources including Carlsbad Caverns National Park, which is a UNESCO World Heritage Site.
A Brief Geologic History—Chihuahuan Desert Network
A few examples of events and Network resources in each geologic time period are highlighted below, from youngest to oldest.
An extensive Cenozoic history is preserved at Big Bend including rocks representing all Paleogene and Neogene epochs spanning from the Paleocene through the Pleistocene. Volcanic flows, talus slopes, pediments and graded plains extend from these mountain highlands. The Chisos Mountains are surrounded by huge fan-like aprons of sediments. Dikes and sills are exposed in and around the pediments. From oldest to youngest, the Cenozoic stratigraphy of Big Bend includes the Hannold Hill Formation (early Eocene), Canoe Formation (middle Eocene), Chisos Formation (middle Eocene– early Oligocene), South Rim Formation (early Oligocene), other Oligocene volcanics, Delaho Formation (late Oligocene–middle Miocene), Banta Shut-in Formation (late Miocene) and Pliocene–Pleistocene alluvium. Fort Davis is located in the Davis Mountains of west Texas and the geology is dominated by thick Cenozoic volcanics documented in three concordant volcanic units of late Eocene age (Everett 1967). White Sands, in the Tularosa Basin, has no exposures of lithified bedrock, instead being covered by a variety of unlithified sediments pertaining to the Quaternary Lake Otero system (KellerLynn 2012).
The Mesozoic geology of the Chihuahuan Desert Network is represented by Cretaceous units within Amistad, Big Bend, and Rio Grande Wild and Scenic River. The Cretaceous geology exposed within Amistad includes the Salmon Peak Limestone, Devils River Limestone, Del Rio Clay, Buda Limestone, and the Boquillas Formation. The grand cliffs that bound the Pecos River in the vicinity of Amistad are composed of Lower Cretaceous Devils River Limestone which represents some of the most complete exposures of Lower Cretaceous rock in North America (Kerans et al. 1995). Big Bend’s Mesozoic section is dominated by marine and terrestrial deposits from the Cretaceous. The thick Cretaceous sequence includes the terminal Cretaceous–Paleogene transition. The Cretaceous sequence in stratigraphic order includes: Glen Rose Limestone, Telephone Canyon Formation, Del Carmen Limestone, Sue Peaks Formation, Santa Elena Limestone, Devils River Limestone, Del Rio Clay, Buda Limestone, Boquillas Formation, Pen Formation, Aguja Formation, Javelina Formation, and Black Peaks Formation. Most of this sequence, from the Glen Rose Limestone to the Pen Formation, is also exposed within Rio Grande Wild and Scenic River.
The Paleozoic geology of the Chihuahuan Desert Network is represented at Big Bend, Carlsbad Caverns, and Guadalupe Mountains. Big Bend preserves a series of Paleozoic units which range from Ordovician to Early Pennsylvanian in age. During the Paleozoic the Big Bend area was situated within a northeasterly trending trough called the Ouachita Trough. The trough was submerged by marine seas and was a depositional center for continental sediments. Maxwell et al. (1967) refers to the Paleozoic sequences at Persimmon Gap as undifferentiated limestones, chert, novaculite, and shale from the Maravillas, Caballos, and Tesnus formations. The Tesnus Formation is Late Mississippian to Early Pennsylvanian in age with marine and non-marine units (Fan and Shaw 1956; Noble 1992). The lower unit of the Tesnus Formation consists of massive and interbedded marine sandstone turbidites and siliceous shales. The upper unit is predominantly non-marine and consists of fine-grained clastic sediments.
Permian strata are well-exposed at Guadalupe Mountains and Carlsbad Caverns in the Guadalupe Mountains of west Texas and southern New Mexico. A large normal fault defines the western flank of the Guadalupe Mountains, while the eastern edge is marked by the Capitan Reef escarpment. The reef escarpment preserves the Permian depositional profile of the Delaware Basin. The Capitan Reef is exposed in both Guadalupe Mountains and Carlsbad Caverns. At Guadalupe Mountains the reef consists of an uplifted block forming a prominent mountain range. At Carlsbad Caverns the reef is exposed in the same uplifted block but is at lower elevation due to a regional dip.
Three areas in Guadalupe Mountains have been designated by the International Union of Geological Sciences as Global Stratotype Sections for the middle Permian Guadalupian Series of the geologic time scale along with their component Roadian, Wordian, and Capitanian Stages (Henderson et al. 2012). The middle Permian is known worldwide as the Guadalupian Series.
The middle Permian Artesia Group (Tansill, Yates, Seven Rivers, Queen and Grayburg formations) and the Capitan Limestone are the primary geologic units exposed in both Carlsbad Caverns and Guadalupe Mountains. Older units representing the early and middle Permian are mapped at Guadalupe Mountains and include the Bone Spring Limestone, Victorio Peak Formation, Cutoff Formation, Brushy Canyon Formation, Cherry Canyon Formation, Goat Seep Dolomite, and Bell Canyon Formation.
The Chihuahuan Desert Network parks do not include any exposed or mapped Precambrian rocks within the park boundaries.
Type Sections—Chihuahuan Desert Network
The geologic history above is excerpted from a report titled, "National Park Service geologic type section inventory: Chihuahuan Desert Inventory & Monitoring Network". Type sections are essential reference locations for the geoscientists who study geologic history and paleontology. A summary of the type sections in each park can be found at the links below.
Amistad National Recreation Area, Texas (no designated stratotypes identified)
Big Bend National Park, Texas [Site Under Development]
Carlsbad Caverns National Park, New Mexico (no designated stratotypes identified)
Fort Davis National Historic Site, Texas (no designated stratotypes identified)
Guadalupe Mountains National Park, Texas [Site Under Development]
Rio Grande Wild and Scenic River, Texas (no designated stratotypes identified)
White Sands National Park, New Mexico (no designated stratotypes identified)
The full Network report is available in digital format from:
Please cite this publication as:
Henderson T, Santucci VL, Connors T, Tweet JS. 2021. National Park Service geologic type section inventory: Chihuahuan Desert Inventory & Monitoring Network. Natural Resource Report. NPS/CHDN/NRR—2021/2249. National Park Service. Fort Collins, Colorado.
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Last updated: December 23, 2022