Among articles to appear in 

 early numbers of the Journal 

 of Geology are the following: 



Notes on Principles of Oil Accumulation. By A. W. McCoy. 

 Discussed by Chester W. Washbiirne. 



A Quantitative Mineralogical Classification of Igneous Rocks — 

 Revised. By Albert Johannsen. 



Professor Johannsen's article— to be published probably in three parts — presents 

 the classification whicK he thinks most satisfactory, after years of study of the 

 subject. 



The Great Glass-Sponge Colonies of the Devonian; Their Origin, 

 Rise, and Disappearance. By John M. Clarke. 



Diastrophism and the Formative Processes. X. The Order of 

 Magnitude of the Shrinkage of the Earth Deduced from Mars, 

 Venus, and the Moon. XI. Selective Aggregation of Material 

 in the Formation of the Earth and Its Neighbors. By T. C. 

 Chamberlin. 



(Two of a group of three papers to appear in successive numbers.) 



The fundamental nature of Professor Chamberlin's recent cosmological studies is 



indicated by the titles of these articles. 



The Pre-Moenkopi {P re-Permian?) Unconformity of the Colorado 

 Plateau. By C. L. Dake. 



Compilation and Composition of Bituminous Coals. By Reinhardt 

 Thiessen. 



Dr. Thiessen has studied bituminous coals in great detail, and his article will be of 

 great value to readers interested in his subject. 



The Origin of Gumhotil By George F. Kay. 



Professor Kay presents a satisfactory explanation of the origin of the gumbos 

 associated with glacial drift. 



Paleozoic Diastrophics of the Northern Mexican Tableland. By 

 C. R. Keyes. 



Movements in Crystallizing Magma. By Frank F. Grout. 



The Laws of Elastico- Viscous Flow. II. By A. A, Michelson. 



