This work was begun in 1964 and substantially completed in 1965; at that time conodont zones had been established in North America only for the Upper Devonian, by Clark and Becker (1960) for the Great Basin and Collinson, Scott, and Rexroad (1962) for the mid-continent. Little was known of the conodonts of the New York section; there was almost no information on the Lower Devonian succession, and there was no published account of the Middle Devonian succession.

Tertiary rocks, including sandstone, conglomerate, shale, pyroclastics, tuff, and lava, are preserved in Big Bend National Park and in a much larger area to the west and northwest. Some of the rocks have distinctive characteristics that enable recognition by their lithology. Others are distinctly dissimilar, although they may have been deposited about the same time.

The Bofecillos Mountains area of Trans-Pecos Texas contains a Tertiary volcanic vent and a varied sequence of lava flows, tuff, ash-flow tuff, and associated conglomerate, sandstone, and mudrock; after most of the volcanic activity had ceased, the area was block faulled and later dissected into a rugged high-standing terrain with striking exposures.

Two distinctive subaerial physiographic features that form a substantial portion, by area, of most barrier islands along the Texas coast are the washover fan and the tidal delta. Volumetrically, washover fan deposits and tidal delta deposits form a significant part of each barrier island. The facies types characteristic of these features, together with their geometry and relationships to sediment of the barrier island nucleus on one side, and bay margin on the other, have not been previously described.

This report presents stratigraphic data and interpretations pertaining to the origin of a continental shelf-ocean basin sedimentary complex developed during Lower Cretaceous time in northern Coahuila, Mexico. This shelf was developed within a carbonate depositional regime and provides a specific descriptive example which should be useful in the development of a comprehensive process-response model of shelf origin.