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Permian rocks are the best-known of the Texas Paleozoic. They are widespread in north Texas, where their characteristic red beds are spectacularly exposed in Palo Duro Canyon. The strata are also oil-rich where buried in west Texas, such as in the Midland and Odessa region. This crude oil-rich area is known as the Permian Basin.
The oldest rocks in Texas date from the Precambrian, specifically the Mesoproterozoic and are about 1,600 million years old, and mark the southern limit of the North American craton. These rocks are mostly buried beneath Phanerozoic sediments, but are exposed in the Llano area, where previous Precambrian igneous and metamorphic rocks were ...
The mountains are composed primarily of sedimentary rock with some igneous intrusions. Geologists refer to them as tilted-block fault mountains and in them can be found 1.25 billion-year-old Precambrian rocks, [ 3 ] the oldest in Texas.
The Texas and Oklahoma red beds are sedimentary rocks, mostly consisting of sandstone and red mudstone. [8] The red color of the rocks is due to the presence of ferric oxide. [9] The rocks were deposited during the early Permian in a warm, moist climate, [10] with seasonal periods of dry conditions. [11]
The Montoya Group is the youngest rock formation in the Tobosa Basin and was formed in the Ordovician Period (485.4–443.8 mya), and sit directly on the igneous and metamorphic basement rocks. The rocks from the Montoya Group are described as light to medium grey, fine to medium grained crystalline calcareous dolomite.
Llano Uplift - geologic map. The Llano Uplift can be considered an uplift by either its pattern on a geological or structural map of the top of the Precambrian rocks. It qualifies as an uplift because it consists of an extensive Precambrian basement high that is exposed by virtue of its surface lying significantly above in elevation the surface of surrounding Precambrian basement.
There are very few rocks of Jurassic age in Texas. [4] The only known Jurassic fossils of Texas come from the Malone Mountains which preserve ammonites, gastropods, and pelecypods. [6] The Cretaceous, by contrast left a rich local fossil record. Due to the alternating rising and falling of local sea levels a variety of life from both land and ...
This article contains a list of fossil-bearing stratigraphic units in the state of Texas, U.S. Sites. Group or Formation Period Notes Admiral Formation: Permian: