Age of the Cincinnati Anticlinal . — Fberste. 97 
leys. This condition was at the maximum just before the Pleisto 
cene period. 
The closing of portions of the old Laurentian valley into water- 
basins occurred during and particularly at the close of the Pleis- 
tocene period, owing, in part, to Drift filling some portions of the 
original valley, but more especially to terrestrial warpings of the 
earth's crust, which, to a sufficient degree, is measureahle. 
THEAGEOFTHE CINCINNATI ANTICLINAL. 
T'.v An;. V. FOERSTB, Cambridge, M:ikn. 
Exposures of Cincinnati group formations in southwestern 
Ohio, even when of considerable length, show a striking horizon- 
tal disposition of strata. Only when outcrops from distant local- 
ities are compared can their connection with the Cincinnati 
anticlinal axis lie recognized. By many this axis is believed to 
have advanced beyond incipient stages of formation, if not to 
have attained complete development, in Lower Silurian times. 
Even ripple marks, mud cracks and rain drop impressions are 
cited from the Cincinnati group rocks of anticlinal regions, in 
support of contemporaneous shallow water conditions. Accept- 
ing the validity of this evidence for the present, how does this 
prove that shallow water conditions, thus inferred, were caused by 
the presence of the Cincinnati anticlinal axis, and were not also 
prevalent in neighboring regions now forming the lower flanks of 
the axis. Until ripple marks, mud cracks and rain drop impres- 
sions can he shown to characterize the axial, more elevated 
regions of the anticlinal, and to he absent from its less elevated 
thinks, no such wide and general deductions can he made with 
safety. 
Consistent with the view which places the incipient or even tin 1 
final development of the Cincinnati anticlinal axis in Lower Silu- 
rian times, later strata of Upper Silurian, Devonian and Carbon- 
iferous age. are believed to have been deposited, with this 
anticlinal axis as their core, and its debris as the source of the 
materials necessary to their formation. As evidence of such a 
relation a conglomerate is cited already from the base of the 
Upper Silurian format ions surrounding this axis, in the Clinton 
