INTRODUCTION. 323 



stone, and 5. The Alluvial. This was published in the 

 Transactions of that excellent Society, and in the first 

 and third volumes of the Medical Repository. Mr. Vol- 

 ney, who has written the best account of the mountainous 

 chains and atmospheric currents in the United States, did 

 me the honour to quote my performance with respect. 



Since that time, tours to Lower Canada and Quebec, 

 to Niagara and the adjacent part of Upper Canada, and to 

 Virginia, have contributed to increase my knowledge ; 

 as have also several journeys by land and a voyage by 

 water, to explore Long-Island and the rocks, islands and 

 shoals in its vicinity. My information too has been ex- 

 ceedingly increased by the intercourse with sensible men, 

 and by the acquisition of fossil specimens. 



On a survey of the whole ground, it appeared to me 

 there was room for a geological classification in a four- 

 fold order ; thus, 



1 . The most ancient foundation of the globe. 



2. The depositions from inland seas or reservoirs of 

 salt water. 



3. The depositions from fresh water. 



4. Modern depositions from the briny ocean. 



During this period, individuals in several places began 

 to form mineral collections, and to travel for the sake of 

 procuring information and specimens. 



In a particular manner, William Maclure, Esq. took 

 a broad survey of the Fredonian States, and deline- 

 ated upon a chart the several geological regions ac- 

 cording to the system of Professor Werner. He com- 

 posed a memoir, in explanation of his map, which is 



