278 CORALS AND CORAL ISLANDS. 
Another improbability. — So great a subsidence is declared 
improbable. The thickness of coral limestone, attributed un- 
der the theory to some coral-reef formations, is pronounced 
by Dr. J. J. Rein* to be far beyond that of any reefs of earlier 
time, and therefore improbable. But precedent, whether a 
fact or not, settles nothing. Coral-made limestones are not 
essentially different in origin from shell-made limestones ; 
and the past year we have reported from Mexico, by Dr. C. A. 
White, a Cretaceous limestone, having similar fossils from 
bottom to top, and yet 4,000 feet thick. It could not have 
been made, as Dr. White states, without 4,000 feet of slowly 
progressing subsidence, for the fossils prove that it is not of 
deep-water origin. Nevada has Devonian limestones, accord- 
ing to Hague and Walcott, 6,000 feet thick, and some simi- 
lar fossils in the upper and lower portions which are proof 
of a gradual subsidence. No thick formation of any kind of 
rock was ever made, or could be made, by shore or shallow- 
sea operations without a slowly continued subsidence or a 
corresponding change of water level. 
But there is another improbability and it is the most im- 
probable of all suppositions that can be made with regard 
to the globe; that, while the continents have had their great 
changes of level, both upward and downward by the thou- 
sands of feet, the oceanic basins, of nearly three times the 
area, and volcanic in the constitution of many high islands, 
have had no changes of level except some local elevations, 
for this is implied by the objectors; not a subsidence any- 
where of a thousand feet or even a hundred, in the breadth 
of thirty millions of feet between America and the East India 
Seas. Whence this stability ? 
1 Dr. Rein’s Memoir on Bermuda is mentioned in the note on page 218. The 
above argument is given here from the citation by Dr. Geikie, the publication not 
being accessible to the writer. . 
