Rocks and minerals of North Texas and Southern Oklahoma. Rocks underlying the DFW region formed in the Cretaceous Period, about 100 million years ago. Cretaceous paleogeography of the U.S. North-Central Texas was under a shallow subtropical ocean during most of this period. Geology of Dallas County.
Numbers refer to field trip sites.
Woodbine Sandstone on the Tarrant County border. Eagle Ford Shale in western Dallas County. Austin Chalk in central Dallas County. Taylor Marl in eastern Dallas County. These features resulted in the Arbuckle Mountains of Southern Oklahoma.