HOT SPRINGS, ARKANSAS. 



83 



shown in the following table, in which the youngest beds are placed at 

 the top of the column and the oldest strata at the bottom. 



Geological age. 



Thickness 

 of beds. 



Character of rock. 



Carboniferous . 



Lower Silurian . 



Feel. 



12 



5 

 100 



75 



38 



200 



230 



20W 



200 



Shales; gray or black graphitic shales with fragments of 

 plant remains, red and yellow colored when altered. 



Sandstone, impure and clayey, with softer layers alternat- 

 ing with softer material. 



Quartzose sandstones, passing at times into conglomerates 

 and well exposed along the basal slopes of Hot Springs 

 Mountain. 



Novaculite breccia. 



Impure novaculite, with iron and manganese. 



Novaculite in thick and thin beds, with some layers of sili- 

 ceous shales. 



Sandstone passing into novaculite. 



Shale, siliceous, and passing into novaculite.' 



Massive novaculite, from which whetstone is taken. ■ 



Shale, siliceous, with thin layers of novaculite. 



Impure novaculite. 



Shales, red and green and gray, with siliceous layers. 



Shales, black, and carrying fossil remains (graptolites). 



Limestone, thinly bedded, blue, aud generally argillaceous. 



Sandstones. 



The rock structure. — Near the Hot Springs these rocks have been 

 compressed into great folds which now form the mountains, and this 

 compression is so great that the folds have been pushed over, or over- 

 turned, and in the gorge of Hot Springs Creek the section now exposed 

 shows the younger beds resting beneath the older ones. In addition 

 to this there has been some faulting in Indian Mountain, by which 

 an overthrust has pushed up the older beds over younger ones. For 

 this reason the section, as given above, is not always easily made out, 

 but it can be seen in the slopes of West Mountain, although, as will be 

 noted there, the younger beds lie below the older and the rocks have 

 a dip of from 25° to 70°. The Carboniferous shales, which are the 

 youngest rocks of the district, are well exposed on Malvern avenue 

 near the Park Hotel, where the olive-colored, sandy shales have been 

 found to contain plant stems and fragments of fern fronds. The shales 

 are rarely indurated enough to form slates, though a few quarries have 

 been opened in them and slate of a poor qualit}^ extracted. Where 

 the shales are slightly altered they are sometimes valuable for brick 

 and terra-cotta burning, though most of the clay used for that purpose 

 is derived from the disintegrated material washed into the creek 

 bottoms. 



The sandstones are of variable texture and composition. The coarser- 

 grained rocks are nearly pure quartzose sand, but the intermediate 

 beds are quite clayey. The chief sandstone horizon seen at the springs 

 is the one lying just above the novaculites, and this rock is the one 

 which is so prominent on Hot Springs Mountain and West Mountain. 



The novaculites are the most interesting rocks of the region. They 

 consirt of nearly pure silica, containing less than one-half of 1 per 

 cent of other material. The rock is very dense, homogeneous, of a 

 cream or white color, and fine grained, resembling in appearance the 

 finest Carrara marble. These rocks are used for whetstones, the finer- 

 grained form being called Arkansas stone and the coarser-grained rock 

 the Ouachita stone. This material has a marked conchoidal fracture 



