Proceedings of tlie Ohio State Academy of Science 23 



of the United States. This necessitated a topographic base map, 

 which was at once started. In 1886 the Survey had pubHshed 

 maps of a small area in the Appalachian mountains, and of one 

 or two small areas in the far west. Today hardly any consid- 

 erable part of the country is wholly unmapped, and the work is 

 being rapidly pushed to completion. The influence of this work 

 on the progress of geolog}' it would be hard to estimate. The 

 Survey began publishing the geological map in the form of folios 

 in 1894; and to date nearly 200 folios have been issued. 



In 1886 no national geological society existed in the United 

 States, and no magazine devoted exclusively to geolog}-. Both 

 of these deficiencies were soon made good, for in 1888 the 

 Geological Society of America was founded, and the publication 

 of its Bulletin was commenced. In 1888, too, the American 

 Geologist was started, to be continued after 1905 as the Economic 

 Geologist. In 1893 the first number of the Journal of Geology 

 was issued. 



Today the texts of Dana and Le Conte have been somewhat 

 generally superseded. Scott's Introduction to Geology and Cham- 

 berlin's and Salisbury's College Geology are the common college 

 texts, while the American manual is Chamberlin's and Salisbury's 

 Geologx in three volumes, which, in the opinion of many, is the 

 leading text of today in its presentation of the principles of the 

 science. 



THE STUDY OF LAXD FORMS. 



In no department of geology has greater progress been made 

 than in the study of land forms. Geolog)- is the history of the 

 earth. That history, until recently, has been read almost ex- 

 clusively, from the rocks, from their distribution, structure and 

 fossils. But we now know that the histor\- of later geological 

 time can be read also from the forms of the land surface, that 

 streams in particular shape the land to characteristic forms, and 

 that these forms in turn can be used to give us the history of the 

 land's surface. The older geology, dealing with rocks primarily, 

 was largelv the study of former areas of deposition, of water 

 bodies. Today geolog)- has, in the study of land forms, a means 



