OF THE UNITED STATES. 42? 



The map of the United States on which those divisions are 

 delineated, though I believe the best yet published, is exceed- 

 ingly detective in the situation and range of mountains, cour- 

 ses and windings of rivers &c. but as the specimens which I 

 collected every half mile, as well as the boundaries of the dif- 

 ferent formations, are from the positive situations of the differ- 

 ent places, the relative arrangement of the map cannot change 

 them, but must become more exact, as the geographical part 

 is made more accurate. 



In adopting the nomenclature of Werner, I do not mean to 

 enter into the origin or first creation of the different substances, 

 or into the nature and properties of the agents which may have 

 subsequently modified or changed the appearance and form 

 of those substances; I am equally ignorant of the relative pe- 

 riods of time in which those modifications or changes may have 

 taken place; such speculations are beyond my range, and pass 

 the limits of my inquiries. All that I mean by a formation, is 

 a mass of substances (whether adhesive, as rocks; or separate, 

 as sand and gravel;) uniform and similar in their structure and 

 relative position, occupying extensive ranges, with few or no 

 interpolations of the rocks belonging to another series, class, or 

 formation; and even where such partial mixtures apparently 

 take place, a careful examination will seldom fail to explain 

 the phenomenon without shaking the general principle, or 

 making it a serious exception to the rule. 



In the account of the metals and minerals, it is not intended 

 to give a list of the number, extent and riches of the metallic 

 and mineral repositories; the nature of the ore or mineral, with 

 a description of its relative position, in regard to the surround- 

 ing substances, is the principal object of geology, which cannot 

 be understood by microscopic investigation, or the minute ana- 

 lysis of isolated rocks and detached masses; this would be like 

 the portrait painter dwelling on the accidental pimple of a fine 

 face : the geologist must endeavour to seize the great and pro- 

 minent outlines of nature; he should acquaint himself with her 

 general laws, rather than study her accidental deviations, or 

 magnify the number and extent of the supposed exceptions. 



