THE CENTRAL BASIN OF TENNESSEE. 99 



light blue (almost white) limestone. The top bed is weathered, long 

 thin projections sticking out in various ways. The softer portions of 

 the bed have been taken out, apparently by the rain beating against 

 the face of the cutting. 



Although for the most part the beds of the Basin are almost hori- 

 zontal with only a slight dip to the northwest, there are many local 

 dips of various angles and in different directions. This is due to the 

 dissolving of the thin clayey seams found as partings between many 

 of the beds. Wherever these dips are found forming a synclinal 

 valley there is sure to be a small water channel down the bottom, dry 

 mostly, but in wet weather full of muddy water of the same colour as 

 the enclosing beds. 



In transportation of the material destroyed by weathering the 

 drainage of the country forms the great agent. 



For drainage purposes the area of the Central Basin may be divided 

 into three divisions and named after the three rivers flowing 

 through it. 



In the northern division we have the Cumberland River occupying 

 with its tributaries, the Caney Fork, the Stones River and the Har- 

 peth River, a drainage area of over half the body of the Basin. The 

 Cumberland flows along the northern margin of the Basin within a 

 few miles from the escarpment. No large streams join the river on 

 that side, but it is the receptacle for numerous small creeks which 

 flow over the escarpment. The Caney Fork joins the main I'iver just 

 as it enters the Basin, and the Harpeth not until after it has left it — 

 the latter river having cut a channel for itself through the escarp- 

 ment in a north-western direction to join the Cumberland. The 

 Stones River lies altogether within the Basin. These are supple- 

 mented by numerous small creeks and chaianels forming a complete 

 network of water-courses over the face of the country. 



The course of the Cumberland is a very tortuous one. From Port 

 Burnside in Kentucky at the head of navigation to the island below 



