2&2 ASHLEY — GEOLOGY OF ARKANSAS. [May 13, 



their existence found, or in which the thickness of the beds would 

 indicate a small fold compared with the majority of folds. The 

 evidence in most of these cases is only negative, but many of these 

 so-called minor anticlines may prove to be quite as important as 

 some which better exposures have disclosed more satisfactorily. 



T/ie Prairie Bayou Anticline. — Fig. 17 will give an idea of the 

 structure of the Prairie Bayou anticline and of its accompanying 

 topography, which may be taken as a type of the serrated ridges. 

 The topography is a gentle slope draining from the top of the ridge 

 next north leading to a long narrow valley, perfectly flat and 

 covered by a deposit of novaculite gravel. This little valley is 

 bounded on the south by a nearly perpendicular bluff 100 feet high, 

 at whose base flows Prairie Bayou. From the top of the bluff the 

 ground slopes gently south. 



The anticline was first observed in the prairie from which Prairie 



^Sanders Creels 



Fig. 17. — Section across Prairie Bayou anticline at Sanders Post-office. 



Bayou takes its name in 4 S., 18 W., section 33. At that point it 

 seems to be an overturn of the type CD', Fig. 14 (preceding chap- 

 ter). From here it can be traced up the valley of Prairie Bayou, 

 keeping close to the township line between 4 and 5 S., until in 

 4 S., 19 W., section 31, it becomes a simple anticline. The head 

 of the east and west valley is at this point. It is crossed by the 

 Arkadelphia-Hot Springs road in 4 S., 20 W., section 36, about an 

 eighth of a mile north of the township line. The existence of 

 several good springs on the axis along its western part should be 

 noted. Westward from where it is crossed by the Hot Springs 

 road the country is flat, and no indication of the axis is found until 

 in 4 S., 20 W., section 31, where an anticline brings novaculite to 

 the surface on the Big Hill creek. The ridge is 75 or 100 feet 

 high and half a mile long ; it is probably a continuation of the 

 Prairie creek anticline. 



Valley Fork Overturn. — In 5 S., 20 W., on the line between 

 sections 3 and 4, De Roche creek cuts through a fifty-foot ridge a 



