discovered that a thorough geological survey must be 

 based upon geography, and he constructed a topographic 

 map expressly for the representation of geologic struc- 

 ture. His stratigraphic determinations were based largely 

 upon instrumental measurements and carefully drawn 

 plans and profiles of the land surveys. Thus was inaugu- 

 rated in America a system of geological surveying which 

 has gradually obtained ground until it is practically 

 universal. The anatomy of the earth is exhibited in its 

 topographic forms. Plains, valleys, terraces, hills, and 

 mountains are full of meaning to the geologist, for in 

 them is revealed the deep-seated structure of the earth 

 and the history of that struggle between the great geo- 

 logic powers which is forever in progress and from the 

 throes of which the continents are born. 



The theater of these early operations was near the 

 coast, where the tides of the Atlantic ceaselessly surge to* 

 devour the land. Here his trained eye observed phe- 

 nomena that led to a long system of observation and 

 investigation, by which he ultimately demonstrated that 

 the margin of the Coastal Plain of the Jersey shore is 

 slowly subsiding, and that the sea is steadily enlarging 

 its dominion. This work, as it has progressed through 

 the years until his death, constitutes an important con- 

 tribution to the facts and philosophy of the science of 

 geology which he cultivated. 



In 1864 Doctor Cook was appointed State. Geologist, 

 and held the position until his death. His first task was 

 found in preparing an elaborate exposition of the mineral 

 resources of the State, which had been brought to light 

 by earlier surveys, and he added to these a series of 

 special investigations such as were required for the sym- 

 metric treatment of the subject. This exposition was 

 completed and published in 1868 in a large octavo volume 

 accompanied by a portfolio of maps. He thus at the 



