70 Feathers tonhaugh s Geological Report. 



don and elephant, the victims probably of the movement of their 

 period. The detritus in the common superficial soil of the coun 

 try is an admirable study for the young geologist. The vast col 

 lection of gravelly matter which is found almost every where 

 on the surface is formed from the ruins of rocks of anterior 

 periods, and brought there by the agency of water. There is 

 an immense collection of detritus of this kind at the city of 

 Washington, and especially near the margin of the Potomac, at 

 the western termination of New York avenue, where frag 

 ments even of the fossiliferous rocks of the Alleghany ridges, 

 together with every variety of specimens of the rocks consti 

 tuting the Atlantic primary chain, are found, all of which detri 

 tus appears to be consequent upon their elevatory movements. 



In bringing together these notices and view s, the intention 

 has been merely to give a direction to the investigations and 

 reflections of the student. In the numerous geological treatises 

 which have appeared of late years, he will find the most in 

 teresting details respecting all the phenomena which have 

 been alluded to. Pie will there also find abundant informa 

 tion respecting the metalliferous rocks, and the nature and 

 direction of mineral veins. The subject, however, is too in 

 teresting to pass over without pointing to some phenomena that 

 will be found extremely interesting to those who are turning 

 their attention to mining in the United States, since they 

 constitute some of the principal guides of practical miners in 

 their operations. 



It is worthy of remark that iron, without the use of which 

 man could scarcely have achieved his own civilization, is the 

 most abundant of all the metals, and is found more or less in 

 all the rocks. In the inferior rocks it is found in veins or 

 immense fissures produced by dislocation, in the compact 

 metallic state. Immense masses of this kind are found in the 

 State of Missouri,* in New Jersey, and in Franklin county 

 New York, These have all evidently had a direct subterra- 



* Report 1835, png-e 52. 



