UNCONFORMITY AT BASE OF ONONDAGA LIMESTONE 3009 
clay or dark shale generally marks the unconformity. The follow- 
ing section just north of Newmans Akron Cement Works will 
show the character of the unconformity here. 
NEWMANS CEMENT WORKS SECTION 
Onondaga— Ft. In. 
MiimeStONe ANG DIACKRACHEKt, a. = on 5. 5 < cabbie ies sacks cs bee cee 6 
Cran COEAMIMesSIMESEONED Atta sicrso.. scree eels wie y Feds fe Bisielald » 4-5 
Darkicotiee-coloredicaleareous Shale ....:h5..-. 0. oa cde eine ee ens 2 
Worse aanesmalert Meets. eg nse Gleb ack es va ok base eo oa. 
Interformational clay— 
Bluish gray shale, much like clay, with limestone pebbles......... I 
Cobleskill— 
Drab-colored magnesian limestones: 2.2. s..c5 5 wee ee oe ee ow a 4-6 
Fig. 4 shows the highly irregular and uneven character of the 
eroded surface of the Cobleskill on which the Onondaga was 
deposited. At the large quarry, 1 mile northwest of Akron, the 
stripping of the Onondaga limestone down to the top of the Coble- 
skill has exposed the upper surface of the latter over a surface of 
several hundred square yards. This shows admirably the irregular 
hummocky surface which was covered by the sea during the 
Onondaga submergence. These inequalities in the surface of the 
Cobleskill rise above the troughs which separate them from 4 to 
6 ft. The surface resembles in its irregularity that which may 
often be seen where the residuary clay has been stripped from a 
limestone in the process of quarrying. 
ONTARIO AND OHIO 
The field observations of the writer on the unconformity at 
the base of the Onondaga limestone include sections in both Ohio 
and Ontario. But the recent detailed work of Dr. C. R. Stauffer? 
in these areas on the Onondaga and associated beds will make 
citation of this author’s results, together with some supplementary 
observations of the writer, suffice for this discussion. 
Ontario.—The Onondaga limestone west of Buffalo rests either 
on the Oriskany sandstone or the Salina formation where the 
Oriskany is absent as far west as Springvale, Ontario. To the 
westward of Springvale the Onondaga lies disconformably on a 
t Bull. Geol. Soc. Am., XXIII, 371-76. 
