262 Maclure on the Arrangement and Origin of Rocks. 



duce the same effect, over the whole earth ; but that the 

 stratification of the different materials, follows any regular 

 series of alternation, or that the strata are placed in the 

 same order, one over the other, for any great extent of sur- 

 face appears to me not fully established; I doubt whether 

 the facts when fully and impartially observed in any country 

 will warrant the reception of such a theory. Our continent 

 is the undisturbed extensive field most likely to decide that 

 question, from the vast continuity of alluvial from Long-Isl- 

 and to the Gulf of Mexico, and the immense secondary basin 

 of the Mississippi, both of which are nearly on a level ; 

 each of them consisting of one uniform mass of the same 

 class of rocks, undivided by any high ridge or chain of 

 mountains, offers a situation on a great scale most likely to 

 contain a regular series of alternating stratification, uniform 

 and placed in the same order of superposition. The ex- 

 amination of the above localities is worthy the attention of 

 our active geologists scattered over the whole surface of 

 the United States. 



The volcanic rocks, from their interfering with the two 

 great sweeping theories of the earth's formation, have had 

 the smallest share of impartial examination. Having been 

 generally observed for the purpose of establishing one o r oth- 

 er of the theories, their nature and relative position have of- 

 ten been misrepresented, to serve the views of the different 

 enthusiastic supporters of the two opposite systems. The 

 pendulum by the impulsion of Werner has been long kept 

 in the extreme exaggeration of the Neptunian theory ; now 

 that Werner is dead, it is likely io swing as far in the oppo- 

 site direction, and scorch our globe with fire, as unmerci- 

 fully, as the Neptunians inundated it with water. I have 

 always been of opinion, that there was no good reason to 

 suppose any priority of one formation over the other, but 

 that both were formed in succession agreeably to the uni- 

 form laws by which nature acts. Although beyond the 

 reach of our observation, and to us as yet unknown, it has 

 perhaps been proved by positive facts that the volcanic 

 alternates, often, with the alluvial and secondary, and 

 there is perhaps good reason to believe, that it has been 

 found under the transition in some parts of this country ; 

 that is to say, rocks that from rational analogy, on the ex- 

 amination of their structure and component parts, would 

 rather incline an impartial observer to place in the vol- 

 canic class than in the Neptunian, have been found, appa- 



