abstracts: geology 519 



beyond the edges and ends of which the feldspar has grown and, there- 

 fore, cannot have been pebbles of another feldspar. T. N. D. 



GEOLOGY. — Geology and underground waters of the southeastern part 

 of the Texas Coastal Plain. Alexander Deussen. U. S. Geolog- 

 ical Survey Water-Supply Paper Xo. 335. Pp. 365, with 9 plates 

 and 17 figures. 1914. 

 The report treats of the physiography, geology, and underground 

 water resources of the Texas Coastal Plain between Brazos River and 

 the eastern boundary of the State. Under physiography are described 

 an interesting succession of wolds, with the gentle gulf ward-sloping 

 Cuestas and steep inland sloping bajadas, parallelling the Gulf Coast. 

 The wolds are produced by differential erosion, and they have had an 

 appreciable influence on parts of the stream courses. 



The geologic formations indicated or described include Carboniferous 

 rocks which form the basement on which the deposits of the Coastal 

 Plain rest, undifferentiated Cretaceous deposits, the water recourses 

 of which are not treated at length, and differentiated deposits of Eocene, 

 Oligocene, Miocene, Pliocene, Pleistocene, and Recent age. The general 

 structure of the region is monochnal, the formations dipping gulf- 

 ward, and the successively younger ones outcropping nearer and nearer 

 the coast. Flexures, domes, and faults of relatively minor impor- 

 tance, are recognized. The general artesian conditions of the area are 

 indicated. L. W. Stephens. 



GEOLOGY. — Mineral deposits of the Santa Rita and Patagonia Moun- 

 tains, Arizona. Frank C. Schrader and James M. Hill. 

 U. S. Geological Survey Bulletin No. 582. Pp. 373, with maps, 

 sections, and illustrations. 1915. 

 The Santa Rita and Patagonia Mountains, located in Pima and 

 Santa Cruz counties in southern Arizona, form an irregular range of 

 the Great Basin type. Longitudinal faulting has played an important 

 part in its orogeny, and later faulting has given to many of the surface 

 features, as well as the rock outcrop belts and fissure veins, a north- 

 westerly trend. The range consists fundamentally of a granitic axis 

 of pre-Cambrian (?) rocks which is flanked by overlapping and locally 

 highly tilted sediments which are from Cambrian (?) to Cretaceous in 

 age. All the formations, except the Cretaceous, have been freely 

 invaded by Mesozoic intrusives and all flooded later by Tertiary vol- 

 canics. The structure in general is monoclinal with dip gently to the 



