Marbut.] 48G [March'., 
the inner l»(ir<l('r of llio cmLayiiKMit, 11i()iio;]i the local t'acics in dif- 
ferent parts may vary slicrhtjy from (^aeh other ami from the t^^pe. 
Tlie wide lowland west of the ridge apparently tm-ns around 
the southern end of the rido-e and joins the lowland of the 
Mississii)pi River tlood-j)lain. 
By means, however, of the best maps obtainable and from the 
deseri})tion of the inland border of the coastal plain southwest 
of Tiittle Rock, Arkansas, it is clear that there is a well-defined 
lowland belt extending in that direction holding the same rela- 
tion to the coastal plain as the lowland west of Crowley's Ridge. 
It extends from Little Rock southwestward, faintly defined at 
first l)ut becoming more and more pronounced southward to 
Malvern. Here the Ouachita River enters it from the 
Palaeozoic uplands, turns abruptly along it in a southwesterly 
direction to Arkadelpliia, where it turns abruptly to the southeast 
and escapes from the lowland through a gap in the Tertiary 
upland. The St. Louis L'on Mountain and Southern railway 
follows this lowland from Little Rock to Ai'kadelphia. From 
the latter place the lowland belt turns westward along the border 
of Mesozoic rocks to western Arkansas. It was first clearly 
recognized and described in this area by Prof. Robert T. Hill.i 
Crossing the Mississippi River at the head of the embayment 
a lowland belt, occupying the same relation to the coastal plain, 
extends along the valley of the Ohio River to the mouth of the 
Tennessee ; thence southward as the valley of the latter stream 
to northeastern Mississippi ; thence southward in the flatwoods 
region of Mississippi, and the lowland inland from the Cliun- 
nenugga Ridge in Alabama. 
The lowland west of Crowley's Ridge is seen, therefore, to be 
only a part of one continuous feature extending from south- 
western Arkansas to eastern Alabama. 
Similarly Crowley's Ridge has its homologue in the Lignitic 
Hill Land^ of Kentucky, Tennessee, and Mississippi; the Ten- 
nessee Ridge ^; the Pontotoc Ridge and Noxubee Hill Land of 
Mississippi and the Chunnenugga Ridge of Alabama. South- 
1 Ann. rept. geol. snrv. Ark. 1888, v. 2r, p. 11-12. 
2 McGee, Twelfth Annual report II. S. gcol. survey, p. SCC. 
3 Sallortl. (Jcol. of Teimessee : Sectir)n on peoloiii(:il iiKip ol the State. 
