Geophysical results are interpreted geologically to synthesize a more complete picture of the major crustal features of the Texas Coastal Plain region. Crustal material thickens from the Sigsbee Deep toward northeastern Arkansas. The low-velocity crustal layers ("continental" material) thicken from the Sigsbee Deep to the profile AB, then thin toward northeastern Arkansas. It is suggested that the high-velocity crustal layer (transition zone) is related to a transition (modified) type oceanic crust. The transition zone thickens from the profile AB toward northeastern Arkansas. It is concluded that the thickening of the transition zone is closely related to the regional tectonics of the Texas Coastal Plain region. The geologic evolution of the Texas Coastal Plain is hypothesized to be an orderly, self-generating, wave-like outgrowth of the continental over the oceanic region.