Among articles to appear in early 
numbers of the Journal of Geology 
are the following: 
The Physical Chemistry of the Crystallization and Magmatic Differ- 
entiation of Igneous Rocks. By J. H. L. Voct. 
Types of Rocky Mountain Structure in Southeastern Idaho. By 
GEORGE ROGERS MANSFIELD. 
Cycles of Erosion in the Piedmont Province of Pennsylvania. By 
F. BASCOM. 
Russell Fork Fault of Southwest Virginia. By CuEstEer K. 
WENTWORTH. 
Discussion of ‘‘“Summaries of Pre-Cambrian Literature of North 
America,”’’ by Edward Steidtmann. By T. T. QuIRKE. 
The Nature of a Species in Paleontology, and a New Kind of Type 
Specimen. By Epwarp L. TRoxELL. 
Studies of the Cycle of Glaciation. By Witt1am H. Hoses. 
Diffusion in Silicate Melts. By N. L. Bowen. 
The Pleistocene Succession near Alton, Illinois, and the Age of the 
Mammalian Fossil Fauna. By Morris M. LEIGHTON. 
Theoretical Considerations on the Genesis of Ore-Deposits. By 
RED RASTALL. 
Diastrophism and the Formative Processes. XIV. Megadiastro- 
phism. By T. C. CHAMBERLIN and R. T. CHAMBERLIN. 
