48 ECONOMIC BOTANY OF ALABAMA. 



Geology and soils. — The geology is very simple, the 

 rocks being of the lowest Coal Measures, nearly all sand- 

 stone (a little shale), and the strata very little dis- 

 turbed by faults, folds, or tilting. Toward the western 

 edge the Coal Measures dip beneath the unconsolidated 

 formations of the coastal plain so gradually as to make 

 the boundary between the two on the surface very in- 

 tricate, as explained in the introductory part of this re- 

 port (page 21). The soil is nearly all sandy loam, de- 

 rived from sandstone by weathering, and its prevailing 

 color is yellowish gray or pale buff. It is rather defi- 

 cient in lime and phosphorus, but pretty well supplied 

 with other elements of fertility, and has the advantage 

 of being easily tilled, and responding readily to fertili- 

 zation. 



Topography and hydrography. — The greater part of 

 the plateau stands pretty high — in some places nearly 

 1,000 feet — above the valleys on either side of it (hav- 

 ing a maximum elevation in Alabama of about 1,800 feet 

 above sea-level), but its topography is of the kind called 

 immature by geomorphologists. The smaller streams 

 have not yet excavated their valleys much, while the 

 larger ones, especially toward the edges of the plateau, 

 have cut deep narrow rocky gorges, making some of the 

 most picturesque scenery imaginable, for a country that 

 can hardly be called mountainous. With very few ex- 

 ceptions the streams of this region originate on the 

 plateau and flow off into the surrounding valley regions 

 and coastal plain, and they are mostly small, swift, 

 clear, and not subject to much fluctuation. 



In Winston and Marion Counties and to some extent 

 in those adjoining there are many examples of a pecu- 

 liar type of topography known as "rock-houses."* As 

 one ascends a ravine he will often find at its head a mas- 

 sive overhanging ledge of sandstone with its upper edge 

 horizontal and either straight or concave. A small 

 stream usually tumbles over the ledge in wet weather, 

 while at all seasons there is likely to be water dripping 



*For additional descriptions of this sort of topographic feature 

 see McCalley 2 (17-18, 54), Smith 4 (98-99), Smith 6 (108), Smith 

 7 (405), and Mohr 8 (75-76). 



