THE COASTAL PLAIN OF ARKANSAS 39 



only pines known in Arkansas) were rather connnon, just as in the 

 Eocene region from South Carolina to Mississippi, of which this 

 seems to be a counterpart. (I soon afterwards saw some typical 

 Eocene country near Arkadelphia.) 



Around Arkadelphia I made no quantitative studies of vegeta- 

 tion, but I was taken to one place of considerable interest a few 

 miles west of there, namely, the eastern end of a belt of Cretaceous 

 countr}' which extends southwestward into Texas. In crossing 

 it rapidly I noticed essentially the same kind of soil and topog- 

 i-aphy and treeless horizons and some of the same weeds and crops 

 that characterize the geologically similar black belt or prairie 

 region of Alabama and Mississippi.^ 



Between Arkadelphia and Little Rock the railroad runs so close 

 to the fall-line that much of the scenery can hardly be regarded 

 as typical of the coastal plain. For the first 15 miles or so it 

 keeps pretty close to the Ouachita River, and traverses bottom- 

 lands very similar to those already described. In many places in 

 Hot Spring and Saline Counties are level comparatively open 

 forests of Pinus Taeda, much like some in southeastern Virginia 

 and adjacent North Carolina except for one striking topographic 

 feature, namely, the frequent occurrence of lenticular mounds, 

 a^-eraging perhaps five feet high and forty feet in diameter. Some- 

 what similar mounds are known in most of the other states west 

 of the Alississippi River — but in none farther east — and their 

 origin is still one of the unsolved mysteries of geomorphology.*^ 

 I was not able to identify many herbs in these pine forests, per- 

 haps chiefly because few were in bloom at the time. (Conditions 

 might have been better a little later in the season.) Between 

 Arkadelphia and Little Rock, as elsewhere in the coastal plain, 

 Pinus echinata seemed to be confined to higher ground. 



Leaving the fall-line at Little Rock and going eastward, alluvial 

 bottoms of the usual character begin immediately, and continue 

 without much variation for nearly 20 miles. Then without any 

 perceptible change in topograph}-^, and little if any change in ele- 



*See Bull. Torr. Bot. Club 40:381-384, August, 1913. 



«The latest discussions of them are by A. C. Veatch in U. S. Geol. Surv. 

 Prof. Paper 46: 5.5-.59. 1936; and :\I. R. Campbell in Journ. Geol. 14: 708-717, 1906. 



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