192

The Basement sands are well exposed south of the railroad just east of Grindstone Creek and north near Lambert. Near the latter place bones of a dinosaur (as determined by Professor Cope) were found by the writer in 1886. It was on. this account that the writer then temporarily designated the formation the "Dinosaur sands."

The Basement sands have not been traced in detail across or around the divide between the Brazos and the Trinity in northwestern Parker, southeastern Jack, and southwestern Vise County. There are reasons for believing that they extend a considerable distance northwestward into Jack County, along the region between the drainage of the Trinity and the Brazos.

In the vicinity of Springtown, Parker County, only thin bands of clay and impure limestone, representing the Glen Rose formation, separate the Basement sands from the Paluxy sands. Crossing this divide from Whitt into Wise County, the Basement sands appear upon its northern side beneath less than 20 feet of thin indurated impure arenaceous limestone and clays containing the Glen Rose fauna, which are surmounted by another bed of thick sands of the supposed Paluxy formation.

Three miles southwest of Bridgeport, on the Willow Point and Bridgeport road, the Basement sands are well shown. At this place, at Willow Point, 1 mile west, at Holey, and at a point 7 miles north of Whitt are buttes capped by thin Glen Rose limestones. These buttes, locally known as East and West mounds, 3 miles south of Bridgeport, are very characteristic and marked. Beneath this cap rock are variegated clays from 40 to 50 feet thick. They are blue at the base and red, white, and other tints at the top. They have many calcareous concretions from the size of a walnut to that of a man's head. Below these clays is pack sand to the base of the Cretaceous, attaining a depth of over 60 feet.

In the cross timbers west of Decatur and thence north and east to the Arkansas line the Basement and Paluxy sands become a single undifferentiable formation, owing to a change in the lithologic character of the Glen Rose beds, which separate them southward. Near Decatur this thin parting of Glen Rose between the Basement and Paluxy sands becomes less appreciable and finally dies out, and northward the two sands unite into one great formation, to which the name Antlers sands (from Antlers, Indian Territory) has been given. West of Decatur these combined sands have an estimated thickness of 193 feet between the underlying Carboniferous and the Walnut beds at the "

Am. Jour. Sci., 3d series, Vol. XXXIII, April, 1887, p. 298.