15 



conjectures about the changes it has subse- 

 quentlj undergone. It is, or should be, the 

 result of actual examination into the ar- 

 rangement and structure of the various ma- 

 terials composing our world, or in deduc- 

 tions drawn from such examination. As a 

 consequence of the general diffusion of mi- 

 neralogical knowledge, much attention has 

 been directed to the investigation of the 

 rocks and mountain masses of our country. 



Previous to the year 1812, the published 

 notices on our Geology were few and unim- 

 portant, and little more was known in a ge- 

 ological point of view, of the United States, 

 than that they extended along the coast of 

 the Atlantic, and were bounded on the 

 north by a chain of mighty lakes. Mr. Ma- 

 clure, a gentleman peculiarly qualified for 

 such a task by a familiar acquaintance with 

 the most interesting formations of Europe, 

 commenced a personal examination of this 

 country, which he traversed in various di- 

 rections. The result of his labors was 

 given to the public in 1817, under the title 

 of Observations on the Geology of the United 

 States, This is a bold outline, sketched by 



