Some Recent American Penological Literature. 127 



"Genesis of the Alkaline Rocks," by R. A. Daly. Journ. Geol., 

 vol. xxvi, pp. 97-134, 1918. 

 An examination of recent publications has led the writer to 

 renewed faith in the general explanation for most 'of the alkaline 

 rocks advanced in Igneous Rocks and their Origins. Doubts are 

 expressed as to the validity of some of Bowen's conclusions on this 

 subject. 



"Internal Structures of Igneous Rocks, their Significance and 

 Origin, with special reference to the Duluth Gabbro," by F. F. 

 Grout. Journ. Geol., vol. xxvi, pp. 439-58, 1918. 

 A study of the significance and origin of banded structures, which 

 are found to be in nearly every case parallel to the bounding 

 surfaces of the intrusion. The banding is attributed to convection- 

 circulation during crystallization. 



"Two-phase Convection in Igneous Magmas," by F. F. Grout. 

 Journ. Geol., vol. xxvi, pp. 481-99, 1918. 

 Banding and other parallel structures in igneous rocks indicate the 

 occurrence of convection during cooling. The idea of convection 

 becomes of practical service when applied to banding as an indicator 

 of the form of the intrusion, assisting in locating and orienting bands 

 of magnetite and other economic minerals and estimating their 

 probable position and extent. 



"A Study of the Magmatic Sulfid Ores," by C. F. Tolman, jun., 

 and A. F. Rogers. Stanford University Publications, 1916. 

 A microscopic and metallographic study of ore-bodies of the 

 Sudbury type, associated with basic intrusions. It is concluded 

 that the magmatic ores in general have been introduced at a late 

 stage as a result of mineralizers and that the ore-minerals replace 

 silicates. The process, however, is distinguished from pneumatolysis, 

 since quartz and secondary silicates are not then formed. Two 

 main types are recognized, namely, nickeliferous pyrrhotite- 

 chalcopyrite deposits in norite and gabbro, and chalcopyrite-bornite 

 deposits in norite and diorite. 



"The Nickel Deposits of the World," by W. G. Miller and C. W. 



Knight. Reprinted from the Report of the Ontario Nickel 



Commission, Toronto, 1917. 

 The origin of the Sudbury ores is fully discussed, with detailed 

 descriptions of all the mines : in opposition to the views of Coleman 

 and others the authors consider that the sulphides were deposited 

 from heated waters at a period subsequent to the consolidation of the 

 norite. It is pointed out that the commercial ore-bodies form the 

 cementing and replacing material of breccias along crushed and 

 sheared zones, not in the norite but in the country rock, often at 

 some distance from the contact. Analyses of the norite show little 

 or no evidence of differentiation. 



