Stonewall quadrangle includes part of the southern margin of the Llano region and part of the eastern margin of the Edwards Plateau where most of the plateau suriace has been destroyed by erosion. An east-northeastward-trending lobe of the Edwards Plateau crosses the quadrangle near its southeastern corner.

This volume presents the texts of papers presented at a Symposium...sponsored by the Southwestern Federation of Geological Societies and The University of Texas in Austin, January 29, 1965. Publication was undertaken by the Bureau of Economic Geology in response to numerous requests for copies.

Incidence of bloating among approximately 600 clay samples from East Texas, ranging in age from Gulfian (Late Cretaceous) to Recent, correlates principally with clay mineralogy-and pH--together an indication of bulk composition--and to a lesser extent with texture, loss on ignition, and content of nonclay refractory minerals.

Hye quadrangle includes part of the southeastern Llano region and part of the eastern margin of the Edwards Plateau where most of the Plateau surface has been destroyed by erosion. In the southern part of the quadrangle a narrow lobe of the Edwards Plateau trends east-northeastward from near the southwest quadrangle corner.