268 T. A. Bendrat — JRocks of Cerro de Santa Ana. 



Art. XXI. — The Bocks of the Cerro de Santa Ana on 

 Paraguana, Venezuela / by T. A. Bendrat.* 



During the course of a journey in Venezuela in the summer 

 and fall of 1912 the writer had an opportunity of visiting and 

 studying the rocks of the peninsula of Paraguana. As a result, 

 he offers the following notes as a contribution to the geology 

 of this little known region and has supplemented them by a 

 petrographic description of the rocks collected at this time. 



The geology of the peninsula differs in an important respect 

 from that of the mainland immediately to the south, and of 

 the neighboring islands, in that it contains exposed areas of the 

 granites, gneisses and schists which constitute the foundation 

 of the peninsula, while they are covered with Cretaceous and 

 later sedimentary deposits. It should be noted, however, that 

 the Cretaceous and Tertiary deposits occur also on Paraguana 

 along with the rocks previously mentioned. In Paraguana the 

 basal complex of granites, gneisses and schists has been invaded, 

 probably in pre-Cretaceous times, by intrusive masses belong- 

 ing to the diorite and gabbro families. These form the most 

 prominent elevations of the region and around them have 

 been deposited a Cretaceous series : sandstones and limestones. 

 Among the latter are beds carrying Rudistce. These rocks 

 after long-continued erosion were folded in Tertiary times, 

 probably before the later Miocene. During the latter part of 

 the Tertiary other sediments, which now form by far the great- 

 est part of the exposed rocks of the peninsula, were deposited 

 around the intrusive masses, as well as the remnants of the 

 disturbed Cretaceous beds, and are found to merge without 

 apparent break into Quaternary strata. 



The Cerro de Santa Ana is the highest elevation in Para- 

 guana and was ascended by the writer under circumstances of 

 great difficulty, and its geology studied. The base of this 

 mountain strikes in a general WSW. and ENE. direction, nearly 

 parallel to the north and south coasts of the peninsula ; in 

 breadth it is about 4 kilometers. In the opinion of the writer 

 this mass represents an exposed laccolith composed entirely of 

 basic rocks, weathering a tan-brown in color and of a slate 

 gray on a freshly broken surface. In the lower portion it is a 

 fine-grained diabase, which the writer, ascending the moun- 

 tain from the west, traced up to an altitude of 1050 feet with 

 certainty, and at 1275 feet it was found to give way to a rock 



* The writer desires to express his obligations to Professor N. M. Fenne- 

 man, head of the department of geology of the University of Cincinnati, 

 Ohio, who most generously placed the apparatus and facilities of the depart- 

 ment at his disposal. 



