Review of Recent Geological Literature. 53 
in mountain masses are such as develop only under consid- 
erable load of rock, and consequently at notable depths in the 
earth's mass. 
A comparison of the relative positions of peneplains and 
depth of structure leads to the conclusion that the mountain 
masses must have been more deeply buried at the time of 
development of the structure than they can have been since 
the date of peneplanation. Consequently, between the de- 
formation which resulted in the structure and the accomplish- 
ment of peneplanation there must have elapsed a period of 
erosion of greater or less time. 
It follows that modern mountains are not the effects of 
those forces wMch produced the structures. This conclusion 
cuts at the foundation of the older systems of classification 
of mountains. 
REVIEW OF RECENT GEOLOGICAL 
LITERATURE, 
Indiana Department 0/ Geology and Natural Resources. T^venty- 
Eightb Annual Report. W. S. Blatchley. State Geologist, IKOH. 
This volume maintains the high standard set by former reports 
issued by Mr. Blatchley. The geological map which accompanies 
It is a notable addition to Indiana geology and is worthy of all 
praise. For the first time, Indiana has a geological map worthy 
of the name. 
The report contains the following chapters: The Geological 
Map of Indiana, by T. C. Hopkins; A short description of the Topo- 
graphy of Indiana, and of the rocks of the different geological 
periods of the state, by T. C. Hopkins and A. F. Foerste; The Petro- 
leum industry of Indiana in 1903, by W. S. Blatchley; The Lime 
industry of Indiana in 1903, by W. S. Blatchley; Report of the state 
mine inspector for 1903, by James Epperson; Report of the state 
gas supervisor for 1903, by B. A. Kinney; A Physiographic and 
Ecological study of Winona lake region, by W. M. Mills; The Strati- 
graphy and Paleontology of the Niagara of northern Indiana, by 
E. M. Kindle; Contents of and Index to volumes I. to XXVIII. of the 
reports of the Indiana Geological Survey, by T. C. Hopkins. 
The detailed field-work for the geological map has all been done 
during the incumbency of Mr. Blatchley and is in the main of a 
high order of accuracy. Future studies will make some changes 
in the Knobstone-Harrodsburgh boundary and several outlying 
