20 PLANT LIFE OF ALABAMA. 



the latter rocks, decomposed and converted inmtn into stratified days, 

 form the deep, warm soil of a region noted for its fertility. 



The metamorphic region extends without any interruption from the 

 central belt of sands and gravels along the eastern border of the State 

 nearly to its northern boundary. 



REGION OF THE COAL MKASIKKS. 



The largest portion of the northern part of the State is occupied by 

 the Coal Measures. There are three coal fields recognized, more or 

 less separated by other formations which will be presently referred to. 

 The most southern of these fields is the Cahaba coal field, beginning 

 above the shoals of the Cahaba River. This field is separated from 

 the Warrior field by the Birmingham or Jones Valley toward the 

 northwest, and from the Coosa coal field by the Cahaba Valley toward 

 the southeast. The southern outlines of this region are extremely 

 broken; the strata of the steep rugged hills disturbed by many folds 

 and faidts are deeply furrowed by erosion. The principal part of this 

 region is formed by the Warrior coalfield, a triangular area, with the 

 southern corner at the shoals of the Warrior near Tuscaloosa. The 

 topographical features of the western field are of much greater uni- 

 formity than those of the Cahaba field. In the lower part of the 

 basin proper, where soft shales overlie the lower conglomerate of the 

 Coal Measures, the surface is undulating, the highest swells risi no- 

 most frequently to low hills. Toward the north the hills pass gradu- 

 ally into the table-lands formed by the heavy bedded sandstones of 

 the upper conglomerate, which exhibit an almost horizontal stratifica- 

 tion. These table-lands are the flattened summits of the several con- 

 verging spurs of the Appalachian chain, known north of the Tennessee 

 River as the Cumberland Mountains and south of the river as the 

 Sand Mountains; the latter with escarpments fronting the Tennessee 

 Valley toward the north, and toward the southeast, Blounts .Valley, 

 which is formed by the southern extension of the Sequatchee fold. 

 The table-land lying between Blounts Valley and Big Wills Valley 

 in the southeast is known as the Raccoon Mountain. The table-land 

 of the range forming the eastern border of Big Wills Valley is known 

 as Lookout Mountain, the steep escarpment of which fronts the Coosa 

 Valley. 



This highland area of the Coal Measures presents in its general 

 aspect a somewhat rolling plateau. It rises to an elevation of from 

 1,000 to a little over 2,000 feet above the adjacent valleys. It slopes 

 gently away from the greatest elevations in the north to the north- 

 western limits of the region, where the Coal Measures disappear under 

 the deposits of more recent formations; and to the south, where it 

 passes gradually into the lower hills in the Warrior coal basin proper. 



