Feather stonhaugh 's Geological Report. 43 



mineral structure and true magnetic direction would be of 

 singular importance to the country. No portion of the terri- 

 tory of the United States which I have visited appears to me 

 so complicated in its geological structure, or is certainly 

 so little known, as the area in question, within which all the 

 important beds of anthracite coat are found, and which has 

 been supposed,* but I believe erroneously, to embrace a por- 

 tion of the bituminous coal field of the Western country. 



All the secondary beds of this portion of North America, 

 which are not reached by tide-water, are limited by those 

 ridges, which have a general parallelism to each other, in a 

 direction usually about N. N. E. and S. S. W. It is a re- 

 markable circumstance, deserving much weight in geologi- 

 cal theory, that the general magnetic range of all the transi- 

 tion chains of Great Britain, of the south of Scotland, of 

 Devonshire and Cornwall, of Wales, of the Isle of Anglesea, 

 and of many parts of the European and other portions of the 

 trans-Atlantic continent, has the same line of elevation, the 

 longitudinal axes of the principal ridges as well as those of 

 the minor ones, trending nearly from N. E. to S. W. and 

 several of them having an anticlinal structure ; whilst in many 

 situations the line of direction of the carboniferous limestone 

 and incumbent coal measures is, in Great Britain as well 

 as in the American area I am treating of, unconformable to 

 the tilted strata below, and seldom deviating many degrees 

 from a horizontal line. These parallel ridges come down from 

 the N. N. E. through the Middle States, and pursue a S. S. W. 

 course, until they are cut off in Tennessee by the Cumber- 

 land mountains, the true eastern limit there of the great West- 

 ern bituminous coal field. In the State of Pennsylvania and 

 in Virginia many of them contain rich deposites of anthracite 

 coal, and are apparently prolonged to the south in a contin- 

 uous line, and without material interruption. Yet in places 



* See report of the committee of the Senate of Pennsylvania upon the sub- 

 ject of the coal trade, 1834 -'5. 



