216 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.41. 



As previously stated, Safford and Killibrew and Hayes and Ulrich 

 referred to the TuUahoma certain underlying shales wliich are locally 

 developed along the northern and western sides of the dome. As 

 these shales represent a distinct group — the Kinderhook — the new 

 name Ridgetop shale is here proposed. An excellent development 

 of the Ridgetop shale is seen in the section about to be described, 

 from which the name is taken. 



Geologic section along Louisville and Nashville Railroad, from Bakers to Ridgetop, Tenn. 



Tennesseean : 



St. Louis limestone — Feet. 



Massive gray to blue limestone weathering into the characteristic angu- 

 lar, rather solid chert and red soil, with an occasional specimen of 



Lonsdalia canadense (top of hill) 



Waverlyan: 



Fort Payne chert (Keokuk) — 



Massive to thin bedded, dark gray and drab, siliceous, practically 

 unfossiliferous limestone weathering into a yellow, barren soil 

 full of small plates of chert. These layers rest unconformably 



upon the underlying shales 100+ 



Ridgetop shale (Kinderhook) — 



(i) Light blue to green clay shale holding numerous ostracods and 



bryozoans 15-20 



(h) Arenaceous shales with bands of porous chert, yielding silicified 



fossils 2 



(gr) Light blue to green shale with same fossils as second bed above . 36 

 (/) Unfossiliferous blue shales passing upward into light blue and 



green shales of bed above 4 



(e) Thin bedded argillaceous limestone and compact dark shales 



with numerous fossils 5 



(d) Dark, compact clay shale with few fossils 15 



(c) Fine grained argillaceous sandstone weathering red and forming 



a conspicuous line in the section 1 



(b) Light blue to green unfossiliferous shale 20 



(a) Sandy, unfossiliferous chert 1 



Maury green shale — 



Unfossiliferous green shale 1-2 



Green shale containing phosphatic nodules ^IJ 



Chattanooga shale — 



Carbonaceous black fissile shale containing numerous Cleveland 



shale conodonts and fish teeth in the lower beds 30 



Hardin sandstone member — 



Iron stained conglomeritic sandstone composed mainly of 

 chert and fragments of silicified fossils from older forma- 

 tions, resting upon the eroded top of the underlying Louis- 

 ville limestone. Fish teeth and conodonts of Cleveland 



shale age are associated with the fossils of greater age 0-2 in. 



Silurian-Niagaran : 



Louisville (Bledsoe) limestone — * 



Massive, dolomitic, unfossiliferous limestone 0-17 



Waldron (Newsom) shale 



The town of Ridgetop is situated upon the lower part of the St. 

 Louis limestone. Between the top of the ridge and the railroad 



