314 ASHLEY — CrEOLOGY. OF ARKANSAS. [May 13, 



two factors in the geology are the shales and shaly sandstones and 

 the structure which governs the exposures of these shaly layers. 

 The shaly layers for a number of reasons being favorable for 

 cultivation, the structure that brings the shales to the surface brings 

 culture. 



If on a map of the region all the land under cultivation were 

 shaded, it would be found that instead of being irregularly scattered, 

 the shaded portions would run in belts, some narrow, others broad, 

 while between them in several places would be belts of almost 

 entirely unshaded territory, sometimes several miles broad, and from 

 twenty-five to seventy-five miles long. 



These broad belts of unsettled territory are frequently nearly 

 level, or but slightly rolling, but they are mostly uplands. The one 

 feature which distinguishes them is that they are outcrops of the 

 great sandstone beds which form the upper portion of the columnar 

 section of the Paleozoic strata of this area. 



The strips of well-populated country run east and west, following 

 the structure, and as they are almost exclusively confined to the 

 valleys, the valley features of the topography will be briefly re- 

 viewed. 



On the eastern sheet the largest valley is the Caddo valley, con- 

 tained mostly in township 5 S., and running from the Ouachita 

 river to the divide between the head waters of Antoine creek and 

 the Little Missouri river. It is enclosed on the north by the Trap 

 mountains and Brooks mountain, and on the south by the Chaly- 

 beate mountain and its continuation westward. Its main stream is 

 the Caddo, and in it is contained the best farming land in the area, 

 as well as the largest villages. 



Notice the arrangement of the post-offices in this valley. On 

 the Prairie Bayou anticline are Social Hill and Saunder's. South 

 of them lie, in a line, Maddry, DeRoche, Bismarck, Valley, Point 

 Cedar and Big Elm, not all on the same anticline, but on the major 

 anticline. 



At its western end the Caddo valley is broken into four minor 

 valleys by three ridges : Rock Creek valley just north of Pine moun- 

 tain ; Antoine valley between Pine mountain and Big Bear moun- 

 tain ; Woodall valley between Big Bear mountain and Antoine 

 mountain, and Walden valley between Antoine mountain and 

 Straight and Wall mountains. The valleys in each case take their 

 names from their main streams and are all well settled. 



