226 A. WINSLOW — GEOLOGY OF WESTERN ARKANSAS. 



Historical Sketch. — The geotectoiiic geology of western Arkansas received 

 little or no attention prior to the inauguration of the geological survey of the 

 state now in progress. Shumard, in the report of Marcy's Red river expedi- 

 tion, made in 1854, makes no reference to the subject. In a paper, published 

 in 1854, by Professor J. A. Warder, of Cincinnati, on a Geological Kecon- 

 noissance of the Arkansas River, an attempt is made to locate axes of flexure ; 

 and some of the conclusions have been confirmed by recent work of the state 

 survey. Marcou touches upon the subject in the report of the Thirty-fifth 

 Parallel survey. One of the most noticeable points in Marcou's interpreta- 

 tion of the geology of western Arkansas is the separation of the contorted 

 slates about Little Rock, which he terms " metaraorphic slates," from the 

 overlying sandstones near that place, which he classes as Carboniferous, and 

 which latter, he states, lie horizontally and unconformably upon the former. 

 Beyond this to the westward, all of the various sandstones and shales ex- 

 posed in the Ozark mountains and the Petit Jean mountains, as well as in 

 the bluffs at Ozark and Van Buren, are included by him in the Carbonif- 

 erous. This distinction between " metamorphic slates " and Carboniferous 

 shales and sandstones led to some confusion in fixing the age of the uplifts. 

 The horizontal position of the sandstones at Little Rock seemed to Mar- 

 cou to preclude the idea that the force necessary for the metamorphosis 

 and upheaval of the underlying " slates " could have been exerted posterior 

 to the deposition of the sandstones, while at other localities rocks recognized 

 as Carboniferous had evidently been subjected to such upthrow. He thus 

 adopted an hypothesis of two distinct periods of disturbance, one anterior 

 and the other posterior to the formation of the Carboniferous rocks. Thus 

 the hills at Little Rock, at Hot Springs and at Sulphur Springs are stated 

 to be dislocations anterior to the Carboniferous. 



In the reports of the first geological survey of Arkansas, which was prose- 

 cuted between the years 1857 and 1860, no attempt is made to delineate 

 geologic structure, and the positions of the anticlines and synclines is referred 

 to only in the most disconnected and incidental manner along with the gen- 

 eral descriptions of counties. Failure to consider these features led to most 

 faulty conclusions in the attempt to correlate the rocks of this region with 

 each other, as well as with those of other states. 



Inception of the present Work. — When, therefore, in the autumn of the 

 year 1887, I entered the coal region of Arkansas, preparatory to its study, 

 it was with very vague anticipations ; yet these anticipations were not suffi- 

 ciently vague to preclude surprise, and, as my journey proceeded from point 

 to point, surprise succeeded surprise. The thickness of the rock column 

 which developed itself exceeded all expectations, as did also the number of 

 the beds constituting this column. Instead of horizontal or gently dipping 

 strata such as I expected to find, steep dips seemed to predominate, and the 



