Llano Uplift
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The Llano Uplift is a formation of Precambrian rock, primarily granite, in Central Texas in the United States. It is located in the eastern region of the Edwards Plateau, west of the Texas Hill Country. This area is rimmed by limestone ridges. The region is characterized by exposures of Precambrian rock (especially granite and gneiss at lower elevations, as well as large protruding rock formations such as Enchanted Rock. The area includes several major quarries that mine the distinctive pink granite. Furthermore, the area contains the only known deposits of Llanite.
The area is termed an uplift due to the raised status of the Precambrian rocks in comparison to adjacent, completely buried Precambrian strata. However, the exposures of Precambrian rock are generally located at the lowest surface elevations of the region. This is best pictured by imagining the igneous roots of an ancient mountain range buried entirely beneath newer sedimentary strata, followed by the erosion of the newer strata to the extent that some of the "highest" igneous rocks are exposed.
The ancient faulting that produced the Llano Uplift is believed to be related to that which produced the Marathon Uplift in west Texas. Both may have been formed around the time of the Ouachita Mountains orogeny.