Almost everyone has seen the fossilized remains of prehistoric plants or animals. These might have been the skeleton of a gigantic dinosaur, the petrified trunk of an ancient tree, or the shells of snails or oysters that lived in the great seas that covered Texas millions of years ago.
Three mappable members in the upper part of the Thrifty formation (Blach Ranch limestone, unnamed shale, and Breckenridge limestone), two in the lower part of the overlying Harpersville formation (Quinn clay and Crystal Falls limestone), and six minor lentils, all in the outcropping Cisco group, northern Stephens County, Texas, have been mapped
About 10 miles south of Van Horn, Texas, the Van Horn Mountains rise abruptly above an intermontane plain and extend southward to the Sierra Vieja. The area lies primarily in the southwestern part of Culberson County but extends into Hudspeth and Jeff Davis counties.
Since 1947, the Morton Salt Company's Kleer mine in the Grand Saline salt dome has more than doubled in size. Balk's mapping of the salt structures in the pre-1947 workings showed that (1) the layers of salt near the southeastern border of the dome dip steeply southeast and south, presumably parallel with the dome border.