the Middle Atlantic Slope. 121 



By geologic structure, by topographic configuration, by 

 behavior of streams, and by the various cultural conditions re- 

 sulting from these natural conditions, the Middle Atlantic 

 Slope is separable into three distinct zones : — viz, the Appa- 

 lachian zone, the Piedmont region, and the Coastal plain. 



In the Appalachian zone the rocks are Paleozoic, and are 

 characteristically corrugated by greatly "elongated flexures ; the 

 predominant topographic characteristic of the region is long, 

 parallel ridges separated by flat-bottomed valleys, the whole 

 — save the sharpest ridges — diversified by a plexus of narrow 

 stream -cut valleys and intervening minor hills ; the great rivers 

 wander meanderingly through the mountain ranges while the 

 smaller streams and secondaries generally gather in elongated 

 basins bounded by the ranges, and both large and small streams 

 flow rapidly over the rooky bottoms of narrow, steep-sided 

 ravines or gorges ; and the civil boundaries and the routes of 

 travel and traffic are generally determined by the parallel 

 ridges and greater waterways, while the industries are deter- 

 mined largely by the resources of the rocks — anthracite and 

 other coals, iron, building-stone, etc., — the thin-soiled mountain 

 slopes being unsuited for agriculture and allied pursuits. 



The Piedmont region comprises an area of highly inclined 

 crystalline rocks, abundantly diked, veined and faulted ; its 

 surface is a rather strongly undulating plain without con- 

 spicuous eminences, inclined seaward, and everywhere graven 

 deeply by the larger and to proportionately less depths by 

 the smaller waterways, which thus give origin to endless 

 mazes' of minor hills ; its hydrography comprises the great 

 rivers which meander irregularly through it, and a widely- 

 branching dendritic system of secondary and tertiary drainage 

 in which the individual members have no uniformity in direc- 

 tion, in which the basins are irregularly rounded or pyriform, 

 and in which the divides are low and inconspicuous and con- 

 stantly curving and recurving in labyrinthine convolutions; 

 while, as in the Appalachian region, both the larger and smaller 

 streams are unnavigable and rush rapidly over the rocky bot- 

 toms of sharply cut valleys, the declivity of the streams cul- 

 minating at the seaward side of the zone, where all, river and 

 rivulet alike, descend to tide level in cataracts and rapids. 

 The civil boundaries of the region follow the waterways and 

 transect the divides, the lines of traffic are either confined to the 

 greater valleys or distributed over the surface, and the pursuits 

 of the people are largely determined by the soil and its pro- 

 ducts. 



In the southern part of the area, the Appalachian and Pied- 

 mont zones are sharply separated by the Blue Ridge — the east- 

 ernmost member of the parallel Appalachian series ; but in 



