Geology and Mineralogy. 503 



5. The Geology of Islay ; by S. B. Wilkinson ; with notes 

 by J. J. H. Teall and B. N. Pea.ch. Memoirs of the Geol. Surv., 

 Glasgow, 1907 ; 8°, pp. 82, pis. 8. — This Memoir describes the 

 Geology of Islay and Oronsay with portions of Colonsay and Jura, 

 islands on the west coast of Scotland. In the introduction a brief 

 reference is made to the physical features ol'the islands. A short 

 sketch is given of the progress of geological research in Islay. 

 The special feature of the Memoir is the detailed account of the 

 metamorphic rocks which enter into the structure of Islay, the 

 correlation of the gneisses of the Rhinns of Islay (the western hills) 

 with the Lewisian gneisses of the counties of Sutherland and Ross 

 in Scotland and the description of the sediments overlying the 

 gneisses of the Rhinns which resemble subdivisions of the Torri- 

 don Sandstone in the Northwest Highlands. A detailed account 

 is given of the rock groups in the southeast of Islay which have 

 been linked with Eastern Highland types. The glacial and recent 

 deposits are also described. 



6. Geology and Water Resources of the Bighorn Basin, 

 Wyoming • by Cassius A. Fisher. Professional Paper No. 53 



IT. S. Geol. Survey. — As stated in the introduction, this paper is 

 designed mainly to furnish information regarding geologic 

 structure and the prospects for underground water. A general 

 account of the surface waters is given, including a statement of 

 their present and proposed uses for irrigation, and the economic 

 products of a geologic nature are also described. The region 

 considered comprises the Bighorn basin, a part of the Clark Fork 

 basin, and the slopes of the adjoining mountain ridges, the entire 

 area comprising 8,500 square miles. The basin is floored by 

 Eocene strata overlying Laramie strata of great thickness. The 

 surface is now dissected by streams which flow in deep but broad 

 sloping valleys, bordered by terraces rising to adjoining highlands. 

 Bad-land structure is rather common in these Eocene strata. 



J. B. 



7. The Geology of the Guaynopita District, Chihuahua. A 

 contribution to the knowledge of the structure of the Western 

 Sierra Madre of Mexico ; by Edmund Otis Hovey, Ph.D. — 

 This paper occupies pages 78 to 95 of the volume written by the 

 students of Professor Rosenbusch in celebration of his seventieth 

 birthday. The first pages sketch the general structural features 

 of Mexico, pointing out that the limits of the plateau have been 

 determined by profound faulting, and calling attention to that 

 feature of the surface consisting in the " Bolsons " or basin deserts. 

 Following this introduction the details of the Guaynopita district, 

 lying in the heart of the Western Sierra Madre, are given. The 

 fundamental rocks are gneiss and schist overlain by limestone, the 

 whole now folded. These are capped by a series of eruptives and 

 are cut by granite which Hovey regards as probably of inter- 

 mediate age in the eruptive sei'ies. j. b. 



