252 ASHLEY — GEOLOGY OF ARKANSAS. [May 13, 



in 1887. He worked only in the western part and mapped out 

 twenty folds and faults having a strike of N. 63° E., and connected 

 with a similar number near Hot Springs. 



That he should have found a uniform strike of N. 63° E. is 

 difficult to explain, for the strike is extremely variable, seldom 

 being the same in strata 100 yards apart. At most of the localities 

 cited by him the strike lacks from 10° to 40° of being N. 6^° E. 

 The fact that so many ridges run " transverse to all geologic struc- 

 tural lines," he disposes of by introducing ''some very powerful 

 cause of greater moment than the twenty folds and faults which cut 

 across the tract." But as a matter of fact these ridges are strictly 

 conformable to the structure. The evidences of faulting which he 

 found are all referable to the simple effects of erosion upon tilted 

 beds, some of which are much harder than others. Considering the 

 shortness of the time spent in the region and the obscurity of the 

 structure, even at the best, and that outside of the river channels 

 good exposures are rare and generally unsatisfactory, and that in 

 the first of his field work, where the structure was more evident, the 

 ridges have a trend of northeast-southwest, it is readily seen how he 

 fell into error. 



Subsequent Observers. — From that time until the work herein re- 

 ported was taken up all the work done was such observations as dif- 

 ferent members of the survey made in traversing the region. These 

 observations soon disclosed the errors of previous work, but did 

 not reveal the number or closeness of the axes. 



The Cross Sections. - 



An idea of the folding can be gained from the north-south sec- 

 tions on PL n (see p. 250). 



The Antoine Section. — Fig. i gives a section through the centre 

 of range 23 W. The part in township 6 S. is offset five miles, to a 

 north-south line through Caney Fork P. O. The section in 7 and 

 8 S. is made along Antoine creek. Its striking general feature is 

 the prevalence of south dips and overturned folds except at the ends. 

 The first attempt to make this section gave only one doubtful north 

 dip in shale. Further, the closeness of folding does not diminish to 

 the south. The exposures are mostly sandstone, though in many cases 

 the presence of shale can be inferred from the topography. In the 

 segment through Caney Fork P. O. the topography is controlled by 

 the structure, this being almost the only locality in the whole area 



