The Willis formation of the Texas Gulf coast

The Willis formation, has long been a source of much discussion and. confusion among geologists of the Gulf Coast, and today many of the questions concerning it remain unanswered. The Willis is distinguishable as a coarse gravelly sand, red or reddish-brown in color but grading to pink, yellow, or brown. It is dominantly a coarse sandstone peppered, with pebbles and granules of quarts and chert, and the whole cemented with ferruginous clay and limonite. It outcrops in a belt of dissected ridges and cuestas, typically covered with a dense growth of trees and shrubs, through portions of Newton, Jasper, Tyler, Polk, San Jacinto, Walker, Montgomery, Harris, Waller, Grimes, Austin, Colorado, Lavaca, and Dewitt Counties in Texas. In Dewitt County, it is overlapped by younger formations and disappears to the southwest. On the east, it continues into Louisiana. No fossils have been reported from the Willis. It is overlain by beds of the Pleistocene and underlain by beds of the Pliocene, so from the superposition of beds, it is Lower Pleistocene in age. The Willis was deposited by swollen, surging rivers on a broad flat plain near sea level as the rivers discharged their loads carried from a region of greater relief. These river deltas coalesced to form a continuous blanket of material. Erosion has since removed the upstream portion and the Willis now found at the surface is part of the plain developed at a distance from the mouth of the streams. The gravels of the Mills formation are the chief source of gravel for road surfaces and. for concrete aggregate on the Gulf Coast. Water bearing sands of the Willis formation for the most productive aquifer on the Gulf Coast. It is extensively produced for both public water supplies and Industrial purposes and preferred because of its softness and low mineral content.