Helderberg Limestones in North America. 109 
orrelation of this increased thickness with the change from an 
almost pure limestone to a sandy rock northwards. This points 
o a second source of material for certain of the formations in- 
volved in the anticlinal, from a region north of the Great Lakes. 
Again, the increase of the true Niagara limestones, and later, of 
the Helderberg rocks in going westward from the anticlinal 
through Indiana and adjacent Kentucky, taken in connection with 
similar phenomena along similar horizons in Tennessee, suggests 
that in portions of the palaeozoic series, an origin for sediments 
must also be sought in regions west of the anticlinal. 
The anticlinal, therefore, instead of being itself a source of sedi- 
ment for succeeding formations, seems to have been near the least 
sediment-favored median line of a great sea, into which vast 
amounts of sediments were deposited. Most of these sediments 
were derived from a continent east of the Alleghanies. A large 
share also was probably derived from Canadian areas, then above 
water. During the Upper Silurian and, perhaps, also a part of 
the Devonian, a region west of the Mississippi may have been a 
source for sediment. The coarser sediments were deposited nearer 
the source in each case ; the finer was deposited in regions more 
distant. The Cincinnati anticlinal, taken as a whole, is a region 
where the least sediments were deposits, since it was most remote 
from these sources. It seems to have formed a line of weakness, 
and hence it was natural that the strong folding caused in the 
Alleghanies by a pressure from the east, almost disappearing en- 
tirely before reaching Ohio, central Kentucky and Tennessee, 
should find a last expression in the Cincinnati anticlinal. 
The purpose of this paper was to discuss the age of the Cincin- 
nati anticlinal. A fuller examination into the various statements 
following this discussion, must he reserved for another time. 
THE "HERCYN-FRAGE" AND THE HELDERBERG 
LIMESTONES IN NORTH AMERICA. 
John M. < !l \i;kk, Albany. 
Dr. Novak has been the strongesl supporter among the Bohe- 
mian geologists of the propositions involved iii the " Hercyn- 
Frage," as suggested hy Beyrich and more fulh elaborated by 
Kayser. and he is the firsl to undertake a comparative study of 
