abstracts: geology 539 



GEOLOGY. — Geology and oil prospects of the Salinas Valley-Park- 

 field area, California. Walter A. English. U. S. Geol. Survey 

 Bull. 691-H. Pp. 32, with maps. 1918. 



The rocks of this part of the Coast Ranges are divisible on the basis 

 of their lithologic character and structural reactions into four major 

 units, the pre-Franciscan rocks, largely granitic rocks and schists; the 

 Franciscan formation, with associated basic igneous rocks; Cretaceous 

 dark-colored marine shale and sandstone; and the Tertiary beds, con- 

 sisting of buff to brown weathering marine shale, sandstone, con- 

 glomerate, and fresh-water and subaerial deposits, of variable lithology 

 and thickness. 



The pre-Franciscan, Franciscan, and Cretaceous are older than any 

 rocks known to be oil-bearing in this region, and any area over which 

 they crop out may at once be condemned as not oil bearing. The 

 Tertiary is divided into the diatomaceous shale group (Salinas shale 

 and shale of the Santa Margarita formation) and the underlying and 

 overlying beds. The diatomaceous shales are the probable sources 

 of an}' oil which may be found in this region, and the oil is to be looked 

 for in beds close to the shales, especially those overlying them. 



Long anticlinal ridges and synclinal valleys modified by erosion 

 constitute the larger ridges and valleys as they now exist. The San 

 Andreas fault, which produced the San Francisco earthquake, is the 

 dominating structural feature of this region. 



R. W. Stone. 



GEOLOGY. — New determinations of carbon dioxide in ivater of the 

 Gulf of Mexico. Roger C. Wells. V. S. Geol. Survey Prof. 

 Paper 120-A. Pp. 16. 1918. 

 The determinations of carbon dioxide in water of the Gulf of Mexico 

 recorded in this paper show that the total carbon dioxide increases 

 with depth, that is, with decreasing temperature, and the amounts 

 found are very near though slightly below those required for equilib- 

 rium with atmospheric carbon dioxide, as calculated by Fox's equa- 

 tion. Determinations of the total concentration of base held in bal- 

 ance with the carbonate and bicarbonate radicles were also made; this 

 quantity apparently increases slightly with decreasing temperature. 

 The data presented do not permit an exact evaluation of the "free" 

 carbon dioxide in the water, but a consideration of the uncertain fac- 

 tors upon which computation of the free carbon dioxide rests indicates 

 that the amount is probably so small in the Gulf water that no appre- 



