114 ECONOMIC BOTANY OF ALABAMA. 



heterogeneous material in many places is a few feet of 

 brick-red loam referred to the Lafayette, and over that 

 sometimes sand of still later age.* 



Both superficial formations (if such they are) may be 

 absent, however, — as appears to be the case over the 

 greater part of Washington County — without making 

 much difference in the vegetation; perhaps because all 

 are equally deficient in lime and potash. Where the 

 older formation comes to the surface the uppermost few 

 inches are usually more sandy than the rest, this differ- 

 ence being presumably due to weathering, assisted by 

 vegetation and copious summer rains. 



Pebbles similar to those in the central pine belt occur 

 in the variegated material and sometimes higher up, but 

 they are less abundant than in the Tuscaloosa formation. 

 In some of the more hilly portions, especially a few miles 

 west of Bay Minette, the hillsides are strewn with blocks 

 and plates of coarse blackish ferruginous sandstone, ex- 

 actly like that already described for region 6B. (In both 

 regions it is a favorite material for the construction of 

 chimneys in the rural districts.) Mud is almost as scarce 

 as lime in this region, so that traveling in wet weather 

 is much less disagreeable here than it is in some regions 

 farther inland. 



Topography and hydrography. — The topography dif- 

 fers little from that produced by normal erosion. In 

 most places it is undulating, with streams well devel- 

 oped, and valleys 10 to 50 feet deep. Some of the smaller 

 valleys are rather narrow and V-shaped, while the other 

 extreme, best developed in Washington County, is broad 

 and savanna-like, with the surface perpetually moist, and 

 ventilated by crawfish-holes. The hills are smooth and 

 rounded, except in the rocky places, and the highest are 

 about 350 feet above sea-level. In the southern part of 

 Clarke County the small remnant of this kind of country 

 between the two large rivers stands so high and has been 

 so deeply dissected by erosion that the topography is as 



''Some geologists now regard both the red loam and the sand as 

 mere products of weathering from the material below, but there 

 seems to be about as much evidence against this hypothesis as 

 there is in favor of it. 



