10 HARPER 



isolated peaks (called " monadnocks " by physiographers), of 

 which Stone Mountain 1 is a magnificent example, stand out 

 conspicuously above the rest of the country. The Blue Ridge, 

 extending in its typical development from Pennsylvania to 

 Georgia, borders the Piedmont region on the northwest and 

 includes the highest mountains of Eastern North America. The 

 rocks of this region are chiefly quartzite, sandstone, and marble, 

 and their elevation above the more obdurate granite is explained 

 by the great Appalachian uplift which took place at the end of 

 the Palaeozoic period. 2 



The whole Metamorphic region has doubtless been covered 

 with vegetation since Palaeozoic or early Cretaceous times, which 

 cannot be said of any other part of Eastern North America. 

 There are many evidences, other than geological, of the great 

 antiquity of this flora, the beginning of which doubtless ante- 

 dates the appearance of all species of plants now living. 



2. The Palaeozoic region. This is bounded on the southeast 

 by the Blue Ridge. On the north, just beyond the Ohio River, 

 it is overlaid by glacial drift, and on the west it passes beneath 

 the coastal plain. Three divisions of it are distinguished, though 

 not very sharply defined. The Appalachian Valley region is 

 a rather narrow belt extending from Pennsylvania to Central 

 Alabama, and characterized by long narrow parallel ridges with 

 broad level valleys between them. Northwest of that is the 

 Cumberland plateau, with broad table-lands and narrow valleys, 

 and still farther northwest this flattens out into the "barrens" 

 and prairies of Kentucky and adjoining states. The Palaeo- 

 zoic rocks are mostly limestone, sandstone and shale, and the 

 vegetation covering them probably dates from Cretaceous or, 

 Tertiary times. 



3. The Coastal Plain. This is defined as that part of the 

 North American continent underlaid by Cretaceous and Tertiary 

 rocks and adjacent to the Atlantic and Gulf coasts. 3 It prob- 



1 See Bull. Torrey Club 28: 454, pi. 2g, f. 1. 1901. 



2 For a recent ecological study of the flora of a typical portion of the 

 Blue Ridge see Harshberger, Bot. Gaz. 36: 241-258, 368-383. 1903. 



3 The formations of the same age in the Great Plains region and west 

 of there have nothing to do with the coastal plain. 



