1897.] ASHLEY — GEOLOGY OF ARKANSAS. 241 



FEET. 



Sandstone 900 



Shale 75 



Black shale with fossils 100 



Total 1 1 75 



There is evidence of much shale below the bottom of this section. 

 Section IX. — Section ix is on Boss Allen creek, in 3 S., 18 W. ; 

 it was obtained by Mr. Griswold.^ 



FEET. 



Shale with some sandstone 700 



Sandstone 400 



Novaculites, etc. (Silurian) 



Thickness of the Carboniferous iioo 



Besides these sections, mention might be made of a continuous 

 outcrop of perpendicular sandstone with some thin layers of shale, 

 which forms the east bank of the Little Missouri in 6 S., 26 W., 

 section 25. In this outcrop the beds exposed have apparently a 

 thickness of 1500 feet. 



On the Cossatot, in 6 S., 30 W., section 19, is a continuous ex- 

 posure of arenaceous shale or shaly sandstone giving a thickness of 

 600 feet, which is much greater than the exposure of the same rock 

 elsewhere. 



On the Cossatot, in 5 S., 30 W., section 17, is a fine exposure 

 of sandstone which at this point crosses the river in high massive 

 ledges from ten to twenty feet thick and dipping north 30°. The 

 river cuts through these ledges forming a series of cascades known 

 as the Falls of the Cossatot. The thickness is about 8oo feet. 



Stratigraphic Fositiofi of the Beds. 



(a) The Novaculite Breccia. — The novaculite breccia was only met 

 with in quantity a mile north of Amity (see p. 232). It appears 

 there following the strike of the rocks. Mr. Griswold reports^ a 

 novaculite conglomerate or breccia occurring just at the top of the 

 novaculite series. This is thought by Dr. Branner to be the top 

 of the lower Silurian strata. 



1 Geol. Stirv. of Ark., An. Rep. for 1890, Vol. iii, PI. iii. 

 ''Geol. Surv. of Ark. y An. Rep. for 1890, Vol. ii, p. 300, 



