22 PLANT LIFK <»F ALABAMA. 



vallt'N i> t i":i\('i-sc(l liy (lie Little Mountain fant^c. wliidi owes its oxist- 

 t'licc t(t the SulH-arlumitt'idiis sandstones wliicli lia\e resisted erosion. 

 'Ilie de|)i-ession hetween the main fanii'e (Sand Mountain) and Little 

 Miuuilain w idens l»v tlieif di\ crLience into a l)tdad \allev <»!' the same 

 eliaratter as the main valley. 



Where tho uppermost cherty strata of the Suhearljonit'erous lime- 

 stone form tiie surt'aee rock the surface soil is li«>ht and more or less 

 siliceous. 'Hiis kind of soil })revails chielly toward the northern limit 

 of the \alley. The soil of the river plain proper. r«'stin*^ upon tho 

 lower and more purely calcareous strata, is of j>-reat fertility. 



RIVER SYSTEM. 



Its extensive river system forms a most prominent feature in the 

 physical geography of the State. Many of the larger tributaries of 

 the main channels of drainage are navigable, and their innumerable 

 feeders, the creeks and streams, traverse highlands and ])lains in all 

 dii'«M'tions. ati'ording an abundant water supply in ev'ery part of the 

 State. 



TENNESSEE RIVER. 



Among the principal rivers is the Tennes.see. most remarkable 

 for its anomalous course. It rises in the mountains a short distance 

 beyond the Ijorder of southwestern Virginia, and following mainly 

 a southwestern course it becomes navigable at Knoxville. A short 

 distance south of Chattanooga it cuts its channel through a southwest- 

 ern range of the Cumberland Mountains, and enters Alabama at the 

 northeastern corner at Bridgeport. From this point it Hows in a 

 nearh' uniform southwestern course about 75 miles, when it reaches 

 Guntersville. Here it turns abruptly to the northwest, reaching the 

 Mussel Shoals, 10 miles below Decatur. These shoals are formed of 

 hard, tiinty rocks, over which the water rushes in a series of shallow 

 cascades for a distance^ of about 88 miles, forming an insurmountable 

 o])stacl(» to navigation as far as Florence. From Florence the river is 

 again naviga])le. It takes a northerl}^ turn at Waterloo, and leaving 

 the State near its northwest corner, continues in this direction, and 

 after a course of 2i)6 miles empties into the Ohio River at Paducah, 

 K}'., making the distance from its source 1,037 miles. 



The vast area south of the Tennessee River is in the main drained 

 by the Tombigl)ee River and its tributaries, the larger ])eing the Sip- 

 sey and Black Warrior; and the Alabama River with its trilnitaries, 

 of which the chief are the Coosa and the Tallapoosa. These main 

 channels of drainage find their outlet into the bay of Mo])ile through 

 the IVIobile River, which is formed by their confluence about 50 miles 

 above the river delta. 



