98 The American Geologist. Feb. 1891 
group west of Belfast. Highland county, Ohio. Specimens col- 
lected by Prof. Edward Orton, and kindly loaned to me by Prof. 
•John S. Newberry, show the cement between the pebbles to be 
abundantly supplied with fossils. A dozen species were recog- 
nized. One of these. Stk-topora similis Ileal, has hitherto been 
described only from the Niagara group of Indiana. The remain- 
der are all well known Clinton forms. Among these are Cyclone- 
ma hili.c Conrad. Orihis biforata Schlotheim and Strophomena 
rhomboiJalis Wahlenberg, the easily recognized Clinton forms of 
species also occurring in Lower Silurian strata along this anticlinal 
axis. The Orthis has two plications in the mesial sinus instead 
of three as commonly the case in related representative Lower 
Silurian types in this region. All remaining forms are character- 
istic Clinton species, not represented by close allies in Lower 
Silurian strata. The Clinton age of the conglomerate is therefore 
undoubted. The pebbles however are unfossiliferous; their age 
could therefore not be determined. Still less is it possible to 
designate their source. That they were derived from debris arising: 
from subaerial parts of the Cincinnati anticlinal axis is purely 
conjectural. Their source may have been in exactly the opposite 
direction; it is unknow r n. The lithological character of the 
pebbles does not demand even an original association with Cincin- 
nati group rocks, since there is nothing very distinctive in the 
mere fact that the pebbles are formed of a bluish limestone. 
The pebbles are drab-blue in color, w r ith the exception of one 
pebble with dirty white or brownish white tints. The largest seen 
was two and a half inches long with nearly the same breadth, and 
a quarter of an inch in thickness. From this size they dwindle 
down to small rounded grains. Their contours arc subangular. 
but their angles are rounded. Their surface is not smooth and 
even, like that of pebbles subjected to continuous abrasion, but is. 
marked b} r pits varying from a millimeter in depth to an occasional 
depth of four or five, and a width of six or seven millimeters 
These pits were evidently formed by the corrosive action of tin- 
sea. In the presence of active currents abrasion is naturally in 
excess of corrosion, and pebbles formed under such conditions 
would not show the little pits here in question. The Belfast 
pebbles have evidently suffered, before being imbedded, from cor- 
rosive influences which were in excess of those of abrasion. 
