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.

This guidebook is a reprinting of a field guide prepared by Shell Development Company as part of a three-day industrial short course for full-time college teachers in geology, conducted from March 30 to April 1, 1970, by Shell Development Company, Houston, Texas, in cooperation with AGI Council on Education in Geological Sciences. The guidebook includes excellent summaries and well-illustrated documentation of elastic depositional environments and related facies of the southeastern Texas Coast.

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.

The conservation movement has grown enormously in strength and breadth during the last decade as a result of widespread concern about natural resources and the quality of the environment. The Federal leadership broadened the definition of conservation to applied ecology and thereby put a meaning into the word that went far beyond its original sense. Conservation now includes all of the physical, social, and legal problems attendant on use of the land.