Discover Texas and Explore the Geodiversity and fossils of the Alibates Flint Quarries National Monument
- Wayne Munday
- 9 hours ago
- 4 min read
Alibates Flint Quarries National Monument is a 5.5Km2 site of profound geological and cultural significance in the Texas Panhandle only a 40 minute drive north on the TX-136 from Amarillo. Established to preserve and study its unique flint deposits this National Monument contains hundreds of flint quarries and cultural sites that provide evidence of 13,000 years of human occupation along the Canadian River valley. Managed alongside the Lake Meredith National Recreation Area this landscape is part of the Great Plains Physiographic Province characterised by geological formations shaped over nearly 300 million years. The park contains a fossil record that spans from the Permian Period to the Quaternary and can also be seen on display at the Panhandle-Plains Historical Museum in Canyon.
The Fossils of the Alibates Flint Quarries National Monument
Petrified wood is found along the Canadian River dating back to the Triassic Period and is linked geologically to the Chinle Formation and extensive series of Late Triassic fluvial and lacustrine sediments formed in a semi-tropical environment with a large river system flowing from southeast New Mexico to the northwest and eventually reaching the sea in the Nevada area. Triassic fossils in Lake Meredith National Recreation Area come primarily from the Tecovas Formation which contains petrified wood and fragments of amphibian and reptile fossils.
The Alibates Flint Quarries National Monument has fossilised algae and preserved coral polyps within the dolomite indicating the presence of shallow marine waters. The Alibates Dolomite preserves algal mats or stromatolites that formed in supratidal mud flats within the Panthalassa Ocean.
The Tertiary Ogallala Formation is the most fossiliferous rock with six documented fossil localities in the Lake Meredith area. These sites contain a range of fossils, including bivalves (Texigryphaea), root casts, silicified grass (anthoecia), Celtis (hackberry) endocarps, insect burrows, gastropod moulds, fish imprints and vertebrate remains including turtles.
Pleistocene river terrace sediments have yielded plant debris, invertebrate burrows, gastropods, a mammoth humerus and a Bison latifrons skull. The latter is a rare 40,000-year-old specimen of a female bison and is displayed at the Panhandle-Plains Historical Museum in Canyon.
Additionally there is the Lava Creek B ash bed a tephra layer or geological layer of volcanic ash and other pyroclastic materials that marks the deposition from the super eruption at the Yellowstone Caldera approximately 640,000 years ago. The Lava Creek B ash bed contains crayfish burrows and plant material.
More recently from the last 11,700 years of the Holocene the alluvium, aeolian sand and soils have preserved fossil material include remains of turtles, snakes, owls, hawks, waterfowl, rodents, rabbits, canids, bobcats, badgers, deer, pronghorns, cows and bison.
The Geodiversity of the Alibates Flint Quarries National Monument
The geology of the region reveals a history of environmental transformations where the exposed formations date back to the Permian Period when the Texas Panhandle was near the equator and part of the supercontinent of Pangaea. In the early Permian the Red Beds of sandstone, siltstone, mudstone, gypsum and dolomite covered the landscape. The Red Beds are rich in iron oxides and clay minerals that extends beyond the National Monument reaching as far north as the Black Hills of South Dakota.
During the late Permian a rise in global temperatures led to rising sea levels submerging the region. This marine environment contributed to the formation of Alibates Dolomite a grey rock layer found on top of the local mesas. Derived from organic material such as plankton, shelled animals and corals this dolomite acts as a caprock that slows the erosion of the softer red beds beneath. Subsequent sea-level fluctuations caused the deposition of gypsum particularly visible at Dolomite Point and Plum Creek and contributed to increasing the salinity of the Canadian River.
A Great Unconformity is observed at the Alibates Flint Quarries National Monument. Rocks from the end of the Permian to about 12 million years ago are absent and are likely to have been removed by erosion. However, evidence from the Pliocene Epoch and notably the Ogallala Formation remains as the main rock of the High Plains Aquifer which comprises the largest fresh-water aquifer in the United States.
Alibates flint that gives its name to the National Monument is a unique multi-coloured agatized dolomite or chert. It formed through the replacement of dolomite minerals with quartz from silica-rich water, creating an exceptionally hard material. The varied colours resulted from trace minerals present in the dolomite. Indigenous peoples used only the highest-quality flint for tool-making, discarding inferior specimens.
During the Quaternary Period from 2.6 million years ago the last Ice Age significantly reshaped the landscape as water eroded and carved deep canyons through the existing rock layers. The Canadian River has eroded more than 60 meters of rock creating the striking mesas and breaks seen today. The riverbed varies in width and continues to shift sediments across the valley.
Beyond the geological significance of the Alibates Flint Quarries National Monument is its cultural heritage with the Antelope Creek People who lived in the Texas and Oklahoma panhandles between 1150AD and 1450AD. They have left behind intricate spiritual petroglyphs or rock carvings that depict animals such as bison, antelope, turtles and deer as well as human figures and symbols. The landscape of the Alibates Flint Quarries National Monument combines natural history with human heritage.