GEOLOGY AND MINERALS. The oldest rocks of the State come to the surface in the Central De nuded Region. In the southern part of this re gion, west of Austin, there is a small area of Archaean rock surrounded by a narrow outcrop of Cambrian and Silurian strata. To the north of this there is a considerable area of Carbonif erous formation followed on the northwest along the eastern base of the Llano Estacado by a still larger region referred by some to the Permian, by others to the Jurassic system. An other large area of Paleozoic and early Mesozoic rocks is found in the Trans-Pecos region, where the predominant formation is the Jura-Trias, with small scattered outcrops of Carboniferous and other Paleozoic, together with some recent igneous rocks. The Llano Estacado, like the Great Plains to the north, is of very recent for mation, consisting of lacustrine Tertiary de posits. The southern plateau or Grand Prairie region is older, being of Lower Cretaceous forma tion, and this formation also skirts the central Paleozoic area on the east. It is succeeded on
the east by a band of Cretaceous strata con stituting the Black Prairie belt. Beyond this the entire coastal plain is composed of marine Ter tiary deposits. Workable beds of bituminous coal occur in the central portion of the State, and large deposits of lignite are stretched along the western border of the coastal plain. In the eastern part of the State, near the mouth of the Sabine, petroleum deposits of great extent have been found at a depth of about 1000 feet. Iron and copper ores, as well as lead and tin, oc cur in the southeastern part of the central region, and silver is found in the west. The Trans Pecos region. still but partly explored, probably contains varied mineral deposits, the most im portant being the cinnabar ores found in the Cretaceous limestone in the south. The most important of the remaining minerals in the State are the immense beds of gypsum found in the Permian strata of the northwestern Red Lands.