280 I CHATIOE StS el TeO SiS 
3. Probable top of the Ohio shale as indicated by the line of 
springs, but the upper 7 feet is covered. From the bare summit 
of Bald Knob to base of shales, 325 feet, nearly all of which is 
shown by following the run on the lower part of the hill 
and higher, on its steep western face. The rocks are thin 
black fissile shales, weathering to a somewhat lighter color, 
and some of the pieces contain large numbers of Protosalvinia 
huronensits Dawson. ‘The lower 13 feet, as shown in the high- 
way cutting near the base of the hill, is a thin, light buff fissile 
shale, which weathers to a much lighter color than the shale 
above, and the weathered pieces are often stained red from iron. 
Dr. Orton stated that the base of the series was composed of 
“26 feet of white and blue clays.”* All of this division is 
referred to the Ofzo shale, which in Dr. Orton’s section is called 
the Huron shales,? but they probably represent the Huron, Erie, 
and Cleveland shales of northern Ohio. The thickness of 332 
feet is the same in the two sections - - - - 332 349 
This formation was named the Ohio black slate by Andrews 
in 1870, and described as extending from the ‘Ohio river hills 
in the vicinity of Rockville, Adams county,” northward to the 
hills at Chillicothe, spreading itself across the upper part of the 
Scioto valley and ‘“‘resting upon the Corniferous limestone in the 
vicinity of Columbus.’’3 In 1879 Professor Leslev applied the 
term Ohio conglomerate to the one occurring at the base of the 
Pennsylvanian or Carboniferous series in Ohio, stating that the 
Sharon conglomerate ‘‘is undoubtedly part (or the whole) of the 
Ohio conglomerate.” * While in 1894, Mr. George H. Eldridge 
apparently named a Cretaceous formation in central Colorado, 
the Ohio formation evidently, from exposures on both sides of 
the Ohio creek in the southeastern part of the Anthracite quad- 
rangle.s Of course both of these names are clearly synonyms 
of Andrews’s ‘‘Ohio black slate,’ which in later years has gener- 
ally been shortened to Ohio shale. 
1 bid., p. 646. 2 [bid., p. 645. 
3 Geol. Surv. Ohio, ‘‘ Pt. Il, Rept. of Progress in the Second Dist.,”’ p. 62. 
4 Second Geol. Surv. Pa.. Q?, 1879 (?), Preface, p. 34, and see p. 29. Also see Q3, 
1880, pp. 56f., 45 f. 
SGeological Atlas U. S., Folio 9— Anthracite-Crested Butte Folio, pp. 6,7. In 
the legend of the geologic sheets, save one, it is called ‘Ohio creek formation ;”’ but 
in the text and on the “ Columnar section” the name is given as ‘‘ Ohio formation.” 
