Reviews — Brief Notices. 567 



thorium minerals) are considered, and descriptions given of the more 

 important localities in Portugal, Colorado, Utah, Cornwall, and 

 Bohemia where the ores are commercially worked. The Canadian 

 occurrences are more fully dealt with, and some useful hints are given 

 to help the prospector in his search. 



3. Geology of the Pitchblende Ores of Colorado. By Edson S. 



Bastin. United States Geological Survey, Professional Paper 90, A, 



1914. pp. 5. 

 After a preliminary account of the principal pitchblende-producing 

 localities the occurrence in the Quartz Hill District, Colorado, is 

 considered. From a study of a polished section it appears that pitch- 

 blende crystallized contemporaneously with chalcopyrite, pyrite, and 

 probably grey quartz. The predominant rocks are pre-Cambrian 

 igneous and sedimentary rocks and Tertiary intrusive rocks. A lead- 

 zinc mineralization followed closely a pyrite one, and pitchblende 

 was deposited during the latter and afterwards fractured, the fractures 

 being filled by sulphides of later mineralization. 



4. Cretaceous Exogyras. — Professional Paper 81, Department of 

 the Interior, United States Geological Survey, 1914, is devoted to 

 the description and illustration of Cretaceous Exogyrse from the 

 Eastern Gulf region and the Carolinas by L. W. Stephenson. They 

 are a remarkably beautiful series of shells, being highly ornamented 

 and unlike anything we have in this country. A general description 

 of the deposits, and a map, prefaces the descriptions. 



5. The Jurassic Flora of Cape Ltsburne, Alaska. By F. H. 

 Knowlton. United States Geological Survey, Professional Paper 

 85d, pp. 39-55, pis. v-viii, 1914. 



The Corwin formation of Northern Alaska, containing much work- 

 able coal, has yielded several fossil plants, which show that the beds 

 belong to the upper part of the Middle Jurassic. The flora is most 

 closely related to that of Eastern Siberia, and of the seventeen species 

 found in the Cape Lisburne region eight occur also in Amurland. The 

 general facies is that of Jurassic floras almost all over the world, and 

 this extraordinarily wide distribution leads the author to consider the 

 possible means of dispersal of Jurassic plants. He concludes that 

 there must have been "a practically continuous land connection 

 between the several localities during Jurassic time ", since only the 

 ferns, with their light spores, could have crossed any considerable 

 stretch of water. 



6. Kalgoorlie, Western Australia. — Part i of the Geolopj and 

 Ore Deposits of Kalgoorlie wo.?, issued in 1912 by Messrs. Simpson 

 and Gibson, and we have lately received the second part by Messrs. 

 Feldtmann & Farquharson,* together with the maps of the area. 

 This district is now completed, and its rocks petrographically described. 

 The publications are issued by the Geological Survey of Western 

 Australia, Bulletins 42 and 51, at 5s. the two. 



^ An article, by R. A. Farquharson, F.G.S., on the " Petrology of a portion 

 of the North Kalgoorlie Field ' ' (Western Australia) , appeared in the GEOLOGICAL 

 Magazine for March, pp. 107-14, and April, pp. 148-57, 1914, Pis. V-VII. 



