Post-Fleming Surface Formations of Coastal Southeast Texas and South Louisiana

Abstract

The paper gives a general discussion of the surface formations and surface geology of the post-Fleming belt lying between the coast and the outcrop of the Fleming in southeast Texas and south Louisiana. Data and discussion are presented under four main heads, Physiography, Stratigraphy, Origin and History, and Structure. Under Physiography it is shown that the present physiography indicates the general features of the geology of the area, that is, the subdivision of the post-Fleming group into four formations, Recent, Beaumont, Lissie, and Willis, and the general structure and interrelations of these formations. Under Stratigraphy the present subdivision is correlated with earlier classifications. The formations are described. The Willis, which is a new formation roughly equivalent to the old Lafayette and Reynosa of this area, is named, subdivided into three members, and described in detail. Its relation to the Goliad formation of south Texas is discussed. Under Origin and History the deposition of these formations is credited to the ancestors of the present major streams of the coast. The peculiar stratigraphic and structural interrelations of the post-Fleming formations are attributed to cycles of deposition separated by tilting movements which affected this part of the coastal plain at intervals. Under Structure the regional structure of the formations, local irregularities, methods of mapping, and the relation of surface to subsurface structure are discussed.