Topography: The Big Thicket Basin has been described as shallow bowl or dish, tilted to one side, with the high rim on the interior north and low rim on the coastal south. Eastern and western rims consist of the low ridges that divide the Neches River and Sabine River drainages on the east and the Neches River and Trinity River drainages on the west. Elevations range from about in the north to in the south, dropping as low as at confluence of the Neches River and Pine Island Bayou. Northern regions are characterized by low gently rolling hills and well formed drainage systems of streams and creeks in the landscape. The southern regions are comparatively flat, with poor drainage and support moderately extensive wetlands.