78 TJie American Geologist. Ausust, \m> 
pretation encounters are greater than in that which has been 
presented, viz: 
1. The ocean was present at least immediately after the 
formation of the conglomerate, as evidenced by the collection 
and stratification of the overlying tuff. 
2. The cement of the conglomerate is of eruptive debris, 
which, in several instances observed, is like the overlying tuff. 
This shows that the cement was accumulating at the time of 
formation of the conglomerate, and that therefore the ocean 
was present, and was very likely doing the same work as 
when later it spread the tuff over the conglomerate. The 
immediate proximity of the older trap, which may have risen 
in bold hills, wall account for the coarseness of the lower por- 
tion of the stratum as compared with the upper. 
3. In the overlying (Upper Cambrian) conglomerate are 
boulders and smaller fragments of an earlier conglomerate, 
and from their nature and the proximity of this lower con- 
glomerate, it is necessary to refer such fragments to this con- 
glomerate. 
4. General taxonomic considerations, as already stated, 
point to the existence of a great fragmental stratum separat- 
ing the Norian from the Keweenawan, and it is reasonable to 
look for it where a great valley of erosion, like that of the St. 
Croix, crosses the strike of those formations. 
Still, until further examination shall show more fully the 
extent of this stratum and its nature, the question of its strati- 
graphic significance and importance may be held in abeyance. 
THE HYPOTHESIS OF A CINCINNATI SILURIAN 
ISLAND. 
By Arthur M. Miller, Lexiugtuii, K.v. 
Dr. Keyes has recently* contended for the mythical char- 
acter of the Paleozoic Ozark isle. The writer shares Keyes' 
skepticism, and desires to be included among those w^ho dis- 
sent from the "old island hypothesis" as the usual method of 
explaining isolated areas of older formations peeping out 
from under newer upon the backs of broad dome-like uplifts. 
*Science, new ser., vol. 7, pp. 588-589, Apr. 29, 1898. 
