A description of all post-Weches formations of the Gulf Coastal Plain in the vicinity of Harris County, Texas, and the geologic history of the Gulf Coastal Plain of southeastern Texas are presented. The many deep wells in this region make it a favored area for such an investigation as the one here attempted. A comparison of surface sections with subsurface sections reveals important changes of facies in nearly every formation.
A geosyncline of major dimensions is located near the outer margin of the Gulf Coastal Plain in eastern Texas and Louisiana. The formation of this geosynclinal depression and the accumulation of sediment in it are the dominant features of the Cenozoic history of this region. Tertiary and Quaternary deposits in the vicinity of Galveston, Texas, are estimated to be 35,000 feet thick. The origin of this geosynclinal depression is discussed.