PREFACE. 



No department of the natural sciences possesses 

 greater interest, or leads to more important prac- 

 tical results, than that of Geology. Of late years 

 it has attracted almost universal attention, not only 

 from the fascinating wonders it discloses, but also 

 from its obvious and extensive application to the 

 economical purposes of life. Of such importance 

 has it been regarded, that many of our state legis- 

 latures, as v^ell as the general government, have 

 authorized geological surveys to be made, in order 

 that the natural resources of the country may 

 be brought to light and fully developed. Every 

 American must feel a degree of pride in reflecting 

 that, in a short period, the geological features and 

 mineral treasures of no country on the globe will 

 be better understood or more justly appreciated 

 than those of our own. Already have these sur- 

 veys contributed millions in value to the produc- 

 tive industry of the land ; and every year their 

 importance is more and more demonstrated and 

 acknowledged. 



To the young the study of geology is peculiarly 

 attractive, as the objects of which it treats are ad- 

 dressed to their observing faculties, which at this 



!)eriod are in a constant state of activity. For a 

 ong time, this science was nearly a sealed book to 



