194 A CENTURY OF SCIENCE 



Twenty years ago S. F. Emmons, in a presidential 

 address before the Geological Society of "Washington, 

 divided the history of Governmental surveys in this 

 country into two periods, separated in a general way by 

 the Civil War. The first of these was the period of geo- 

 graphic exploration, the second that of geologic explora- 

 tion. Mr. Emmons of course regarded this subdivision 

 as not hard and fast, yet his dividing line seems logical, 

 for not only did the military activities in the East neces- 

 sarily suspend exploration in the West, but after the war 

 national, political, and economic considerations led nat- 

 urally to the demand for a more exact knowledge of the 

 vast national domain in the West. Geography and geol- 

 ogy are so closely related that Mr. Emmons 's distinction 

 of the two periods is useful only with the limitations 

 inferentially set by himself namely, that while geologic 

 investigation entered into most of the explorations of the 

 earlier period, the geologist was regarded as only an 

 accessory in these exploring expeditions; on the other 

 hand, in the later surveys the topographic work was 

 developed because it was essential to the geologic 

 investigations. 



The year 1818 was a notable one in American geology, 

 first of all in the appearance of the American Journal of 

 Science, itself so perfect a vehicle for geological thought 

 that, as is so well stated by Dr. G. P. Merrill, "a perusal 

 of the numbers from the date of issue down to the present 

 time will alone afford a fair idea of the gradual progress 

 of American geology." The beginning of publications 

 on New England geology appeared that year in Edward 

 Hitchcock's first paper on the Connecticut Valley (1, 105, 

 1818) and the Danas' (S. L. and J. F.) detailed geologic 

 and mineralogic description of Boston and vicinity ; and 

 the " Index" of Amos Eaton (noticed in this Journal, 1, 

 69) was the first of that long list of notable contributions 

 to American stratigraphy that are to be credited to the 

 New York geologists. 



In the present discussion, too, the year 1918 can be 

 regarded as in -a way the centennial of Government geo- 

 logic surveys, for it was in 1818 that Henry R. School- 

 craft began his trip to the Mississippi Valley perhaps 

 the first geologic reconnaissance into the West and it 



