REVIEWS 785 



Petroleum and Natural Gas in Oklahoma. By C. W. Shannon 

 and L. E. Trout. Okla. Geol. Surv., Bull. No. 19, Part I, 

 1915. Pp. 133, pis. 7, figs. 4. 



The great public demand for information concerning oil and gas 

 necessitates the publication, not only of detailed reports on individual 

 fields, but also of papers containing general information regarding the 

 oil and gas business. The present bulletin is designed to meet both 

 demands. It is published in two parts. Part I deals with the general 

 phases of the industry, and includes a short discussion of the geology of 

 Oklahoma. Part II gives a more detailed account by counties of the 

 oil and gas fields of the state. H "R "R 



The Willow Creek District, Alaska. By S. R. Capps. U.S. Geol. 

 Surv., Bull. No. 607, 1915. Pp. 86, pis. 15, figs. 5. 

 An area of 90 square miles at the head of the Little Susitna River, 

 which enters Cook Inlet from the north, is described. The geologic 

 formations are pre- Jurassic mica schists cut by quartzdiorites, and an 

 Eocene sedimentary series with interbedded basaltic lava flows. Alaskite 

 dikes and gabbro masses occur in association with the larger intrusives. 

 Gold occurs in placers and quartz lodes. The latter are quartz-filled 

 fissures in the quartz-diorite carrying free gold and sulphides. 



H. R. B. 



The Broad Pass Region, Alaska. By Fred A. Moffit. U.S. 

 Geol. Surv., Bull. No. 608, 1915. Pp. 80, pis. 8, figs. 3. 

 The Broad Pass region comprises an area of about 3,700 square miles 

 along and south of the axis of the Alaska Range east of Mount McKinley. 

 The oldest rocks are of Devonian age, representing the same general 

 horizon as the Devonian of the Mount McKinley and Porcupine River 

 regions. The Mesozoics are less deformed than the Devonian series. 

 Basic lava flows are apparently overlain by upper Triassic slates which 

 are probably equivalent to the "undifferentiated Paleozoic" series of 

 slates and graywackes along the south flank of the Alaska Range, as 

 described by Brooks, Capps, and Eldridge. A series of slate, graywacke, 

 and conglomerate is provisionally assigned to the Jurassic. At some 

 time before the Tertiary these rocks were folded and intruded by igneous 

 masses. The Eocene is represented by the Cantwell formation, in 

 places intensely folded and cut by granites and diorites. The sections 

 on Quaternary deposits, igneous rocks, and glaciation are by Joseph 

 E. Pogue. H. R. B. 



