Trinity sand and loose slabs of Goodland limestone at rock bluff (Old Marshall bluff) on Red River 8.5 miles northwest of Denison. Grayson County, Texas. 1914.

Trinity sand and loose slabs of Goodland limestone at rock bluff (Old Marshall bluff) on Red River 8.5 miles northwest of Denison. The upper 150 feet of the Trinity is exposed in the bluff. The Goodland limestone, which immediately overlies the Trinity, forms a ledge along the crest of the bluff, and large masses of rocks broken from it have fallen down the slope, giving rise to the name Rock Bluff. Grayson County, Texas. Circa 1914. Plate 19-A in U.S. Geological Survey. Professional paper 120. 1919.