20 
GEOLOGY OF NORTH CAROLINA. 
and broad ridge or swell of land which trends due east along the north- 
era border of the State, preserving for more than 100 miles, an elevation 
of about 800 feet and upwards. It may in fact be regarded as a spur, or 
prolongation of the Pilot and Sauratown mountain range, carrying coast- 
ward almost the elevation of Surry county, (at the foot of the Blue 
Ridge), to the very borders of Granville, and making its last bold effort 
to assert and to emulate its origin in the high knobs and ridges about 
Roxboro, some of which exceed 1,000 feet in height, as Haga’s moun- 
tain, &c. 
In consequence of this structure the drainage along the northern bor- 
der is eastward , the Dan River keeping this average course from the 
Blue Ridge, its channel being sometimes in this State and sometimes in 
Virginia, until it reaches the eastern champaign in Halifax county. A 
second consequence is, that the direction of the slope or greatest descent 
of this section is abnormal, the general course of the drainage waters be- 
ing nearly due south, as is seen in the upper waters of the Tar, Reuse, 
Haw and Deep rivers, as well as several large tributaries of the Yadkin, 
all of which take their rise along the crest of this notable ridge. These 
streams, and also the lower portions of the Yadkin and Catawba, (which 
take the same course, after leaving the piedmont plateau), are separated 
by parallel ridges whose crests descend very gradually from the northern 
divide, several of the more western, preserving an elevation of nearly 
600 feet almost to the southern border of the State. Rear the middle of 
this region, in a northeast and southwest direction, that is, parallel to the 
Blue Ridge and the Atlantic coast, is a succession of elevated ridges and 
knobs, locally called mountains, which are visible one from another, and 
extend from the Uwharrie mountains in Montgomery county, to the 
heights about Roxboro, in Person, already mentioned ; its course being 
marked in the intermediate counties, Randolph, Chatham, Alamance and 
Orange, by the conspicuous elevations known as the Pilot, Hickory, Cane 
Creek and Oconeechee mountains, whose heights are about 1,000 feet 
above sea level. These hard, slaty ridges are doubtless the remains of an 
ancient continuous mountain chain. 
The Piedmont region, a submontane plateau, whose average elevation 
is about 1000 feet, is divided, as to its river systems, into three regions, 
drained respectively by the Broad, Catawba and Yadkin rivers ; the slope 
of the first being towards the southland of the others, a little east of north. 
These drainage surfaces are separated by two nearly parallel easterly 
chains of mountains, the South and the Brushy. The former is a spur of 
the Blue Ridge, and may be regarded as an eastern prologation of the 
Swannanoa range, in Buncombe. It is the divide between the upper 
