REVIEWS 255 



c) The third type of fauhs, to which the name of wrench-planes has 

 been apphed, originates when the greatest pressure is in one horizontal 

 direction, and the least pressure in another horizontal direction, necessarily 

 at right angles to the first. They ''strike" in two possible directions, form- 

 ing acute angles which are bisected by the direction of greatest pressure ; 

 their hade is theoretically vertical. E. W. S. 



The Copper Deposits 0} Missouri. By H. Foster Bain and E. O. 

 Ulrich. (United States Geological Survey, Bulletin No. 267, 

 1905.) Pp. 52, I plate, 2 figures. 



Copper is widely distributed in Missouri in the form of sulphides and 

 carbonates, but the deposits are not large, and only four mines have found 

 it in workable amounts. The total value of copper so far produced has 

 been variously estimated at from $20,000 to $50,000. The ores are believed 

 to have been widely disseminated in crystalline and sedimentary rocks, and 

 to have been concentrated by underground waters. The copper seems 

 related to original shallow water conditions. It also shows a preference 

 for certain horizons. This is believed to be due to unequal distribution at 

 the time the rocks were formed. E. W. S. 



The Geology 0} the New England Plateau, with Special Reference to 

 the Granites of Northern New England (New South Wales). 

 Part II, "General Geology;" Part III, "The Genesis of Ore 

 Deposits." By E. C. Andrews, B.A. (Extract from Records of 

 the Geological Survey of Nevi^ South Wales, Vol. VIII [1905].) 

 Pp. 45, II figures, I plate. 



These papers treat of the geology of New South Wales ; the occurrence 

 of gold, wolfram, tin, monzite, bismuth, and other ores; and the close rela- 

 tion between their occurrence and certain acid intrusives. E. W. S. 



The Geology of the Diamond and Carbonado Washings of Bahia, 

 Brazil. By Orville A. Derby, Translated by J.C. Branner. 



The diamonds occur in various formations, but principally associated 

 with a heavy conglomerate, 6-10"^ thick. About 250"^ of sandstone lie 

 above this conglomerate, and an equal thickness underlies it. Where dia- 

 monds occur in other formations in the region, they are thought to have 

 been transported there from the conglomerate. The structure is Appala- 

 chian in type, and there has been much faulting and folding and erosion. 

 The age of the conglomerate is unknown, but undisturbed Cretaceous 

 sandstone is found near the folded conglomerate. E. W. S. 



