Last Modified: 08/20/09
Below is a brief summary of the geologic history of Texas. A much more detailed geologic history of Texas can be found in your lab manuals.
The edge of the continent coincided with the boundary labeled B on p. 550, Fig. 26-1 in your lab manuals (the present day Balcones Fault System). The Llano Uplift occurred forming a dome.
In the Pennsylvanian/Permian (Late Paleozoic), a plate collision occurred along line B (in Fig. 26-1) that raised up the Ouachita Mountains. Eroded sediment was deposited to the NW (North Central Province).
In the early Mesozoic the Gulf of Mexico began to form. In the Cretaceous the sea transgressed depositing widespread limestones visible from Austin into West Texas (the Edwards Plateau).
In the early Cenozoic (the Tertiary) the sea retreated, establishing the current drainage system (draining toward the SE). These rivers deposited sediments (deltas) along the SE coast of Texas in great thicknesses. Depression of the Earth's crust by the weight of the sediment caused downfaulting along the Balcones Fault System (line B).
Later in the Tertiary crustal stretching and thinning in the Trans-Pecos Region caused volcanic activity and active faulting in that area.
In the late Cenozoic (Tertiary/Quaternary), the Ogallala Formation was produced forming the High Plains. The Ogallala Formation consists of alluvial deposits whose erosional source was the eroding mountains in New Mexico.