Ciiichniati Silurian Island. — Miller. 79 
Our writers of geological text-books, following tradition, 
have without questioning accepted this island hypothesis. It 
seems to harmonize well with the theory of continental growth 
from a central nucleus by progressive elevations, and is iu 
keeping with a general reluctance on the part of these and 
other writers to recognize in erosion the prime factor in bring- 
ing about the exposure of ancient formations. Thus Le 
Conte, while admitting that some such areas may have been 
uncovered by erosion, seems favorable to the "progressive ele- 
vation theory,"'" and again he refers directly to the existence 
of a "large island in Devonian seas in the region of Cincin- 
nati. "t Scott accepts the Ordovician age of the Cincinnati 
archj and the existence during Silurian and Devonian times of 
islands in this region. § 
Dr. Xewberry, as early as 1869, when state geologist of 
Ohio, attributed the exposure of Lower Silurian rocks in the 
southwestern part of the state to the uncovering action of ero- 
sion; but his successor, Prof. ( )rton, argued for the existence 
of the "Silurian Island." 
Recently, also, Weller accepts without hesitation the old 
view of the former existence of all these islands and has them 
play an important role in the early Carboniferous seas.;i In 
attempting to correlate with changes in physical geography, 
the faunal changes recorded in the fossils of the Mississippian 
series, a most kaleidoscopic shifting of land and water areas 
(reminding us of the "catastrophic oscillations" of Woodward) 
is assumed, ^^'ith the meager evidence at command, it is 
hazardous to attempt such paleographic restorations. "Lau- 
rentian land" and "Appalachian land," somewhere in the re- 
gions usually assigned them, there may have been; Paleozoic 
sediments had to come from somewhere; but we believe the 
usual ground upon which the position and outlines of these 
have been deduced is open to question. Extensively denuded 
surfaces of moderate geological antiquity have been mistaken 
for slightly denuded surfaces of great geologic antiquity. Es- 
*Elements of Geology, 4th ed., pp. .308-309, 1896. 
tOp. cit. p. 341. 
jAn Introduction to Geology, p. 378, 1897. 
§0p. cit. pp. 386, 395, 
lljour. Geol., vol. 6, pp. 303-314, Apr.-May, 1898. 
