COLLECTING AREA OF HOT SPRINGS 28 



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beds from three to eight feet thick. The basal ten feet is conglom- 

 eratic. It is from this formation that most of the hot springs issue, 

 which fact, however, is not significant. 



The Stanley shale is composed mainly of black to green clay shale, 

 though a large percentage of it consists of rather soft, greenish sand- 

 stone. This shale skirts Hot Springs and West Mountains. While 

 a large part of the city of Hot Springs stands on this formation, 

 only the waters of those springs that issue at the lowest levels move 

 through it. 



Possibilities of ground-water flowage. — While the altitude of the 

 Boston Mountains is sufficient to give the ground-water enough head 

 for it to emerge at the height and distance of the hot springs, the 

 intervening structure makes such impossible. The closely compressed 

 folds, their lateral overlapping, and the faulting of the Ouachita area 



Fig. 2. — Northwest-southeast section at Hot Springs, i. Bigfork chert. 2. Polk 

 Creek shale. 3. Missouri Mountain slate. 4. Arkansas novaculite. 5. Hot Springs 

 sandstone. 6. Stanley shale. 



to the north and west of the hot springs are such as to prevent the 

 uninterrupted movement of ground- water except for short distances. 

 Likewise the stratigraphy, structure, and topography to their south 

 eliminate that area as a possible source of the water; and the structure 

 of the Appalachian province and the Embayment area is such as to 

 preclude the former as a possible location of the water head. 



The collecting area. — It follows from the above that the collecting 

 area must be in the near vicinity of the springs, and a study of the 

 topography, stratigraphy, and structure thereabout locates it with 

 reasonable certainty. A glance at the section (Fig. 2) from Sugarloaf 

 Mountain southeastward through Hot Springs Mountain will indicate 

 the collectiiig area. The surface of the overturned, anticlinal valley 

 between Sugarloaf and North mountains is higher than the level of 

 emergence of the springs. The rocks outcropping over the area are 

 the Bigfork chert and the Polk Creek shale, the former occupying most 

 of the area. 



