A PLEISTOCENE PENEPLAIN IN THE COASTAL PLAIN 703 



The unbroken surface of this region is due to the homogeneous character 

 of the limestone, which suffers waste equally on this account, over considerable 

 areas; and hence the entire absence of ravines, and other abrupt irregularities. 

 .... In the uncleared parts of the cane brake, .... one can scarcely 

 satisfy himself that he is not standing on the low grounds of a river; the 

 deep, aUuvial-looking soil beneath his feet, the moisture-loving long moss 

 (Tillandsia usneoides) above his head, together with an undergrowth of Sabals, 

 Palmettoes, and other natives of damp soils, strengthen the illusion.' 



Professor Eugene A. Smith's accurate and suggestive description 

 is as follows: 



The Selma chalk underlies a belt entering the State from Mississippi and 

 extending eastward with an average width of 20 to 25 miles, to a short dis- 

 tance beyond Montgomery, where its distinctive characters are lost or merged 

 into those of the "blue-marl region." .... The somewhat uniform composi- 

 tion of the Selma chalk has caused it to be more deeply and evenly wasted by 

 erosion and solution than the more sandy formations north and south of it. 

 As a consequence, its outcrop is in the shape of a trough, with a gently undu- 

 lating, almost unbroken surface except where remnants of the once continuous 

 Lafayette mantle have protected the underljdng limestone from erosion and 

 have thus formed knobs and ridges capped with its loams and pebbles. 



In this belt, more than in any other of the Coastal Plain, the soils show 

 their residuary character. They are, as a rule, highly calcareous clays and, 

 where much mixed with organic matters, of black color. Throughout this 

 section are areas originally destitute of trees and hence known as "prairies." 

 From the agricultural point of view, the Selma chalk or black belt is the most 

 highly favored part of the State and, apart from the cities, holds the densest 

 population.^ 



R. M. Harper^ characterizes the topography as "gently undu- 

 lating in a manner difficult to describe, though probably due 

 almost wholly to normal erosion processes," and points out that 

 "some of the region, mostly remote from the rivers, is so level that 

 the railroads have built straight tangents (i.e., straight tracks) a 

 dozen or more miles in length." He also points out the rarity of 

 swamps. The region is traversed by rivers that are, in most 

 places, bordered by steep, bare bluffs — in some places 60 feet 



' Tuomey's Second Biennial Report, pp. 134-37, 1848, quoted by Eugene A. Smith 

 in his report on the Geology of the Coastal Plain of Alabama (1894), pp. 282-84. 



2 Underground Water Resources of Alabama (1907), p. 13. 



3 Roland M. Harper, "Economic Botany of Alabama," Geographical Report on 

 Forests, Monograph 8, Part i, 19 13. 



