84 REVIEWS 



Maps and Sections to Accompany Report on the Geology and Ore- 

 Deposits of Meekatharra, Murchison Goldfield. Geological Sur- 

 vey of Western Australia, Bulletin No. 68, 1916. Pis. I-XXV. 

 The bed rock of the area consists chiefly of amphibolite and other 

 varieties of schists, into which numerous granitic masses have been 

 intruded. There are also present some extrusives and a few local 

 occurrences of Devonian shales, arkoses, and dolomites. The bulletin 

 consists of numerous geologic maps and sections, and mine maps for 

 the area. 



^_^_____ A. C. McF. 



Maps and Sections to Accompany Report on the Geology and Mineral 

 Resources of the Yilgarn Goldfield. Geological Survey of 

 Western Australia, Bulletin No. i, Pt. Ill, 191 7. Pis. I-XIX. 

 The geology as shown on the maps and sections is essentially the 

 same as found in the other gold fields of Western Australia, consisting 

 chiefly of igneous and metamorphic rocks and a minor amount of sedi- 

 mentary. The report includes detailed maps to the scale of one mile to 

 the inch, as well as more generalized maps on a much smaller scale. 



A. C. McF. 



The Cambrian and Ordovician of Maryland. By R. S. Bassler. 



Systematic Report, Maryland Geological Survey, 1919. Pp. 



424, pis. 58, figs. 27. 



The Ordovician and Cambrian are considered together because of 

 the continuity of the limestone which forms the top of the one and the 

 base of the other. The proposed Ozarkian and Canadian systems are 

 not recognized. Three great phases of sedimentation are recognized, 

 (i) the Lower Cambrian siliceous phase, (2) the great limestone deposits 

 of the Upper Cambrian and Lower Ordovician, and (3) a shale phase 

 covering the Middle and Upper Ordovician, the three forming an 

 aggregate about 16,000 feet thick, of which the limestones form more 

 than half. The first phase mentioned is more or less confined to the 

 Blue Ridge, the hmestones to the Great Valley and Allegheny Ranges, 

 and the shale phase chiefly to the latter. 



The description of formations includes detailed sections, faunal lists, 

 discussion of correlations, topographic features, areal distribution, and 

 economic resources. In many of them distinct faunal zones are recog- 

 nized. There is appended a general faunal list showing the geographic 

 distribution of the forms. 



