OBJECTIONS TO THE THEORY OF SUBSIDENCE. 287 
dition Report describes as nearly a mile wide and yet having 
no channel deep enough for a canoe. The whole amount of 
subsidence estimated in the Report is one to two hundred feet 
— and whatever the amount it may have long since ceased. 
The same conclusion comes from the Florida Bank. The reef 
of Tahiti, on the contrary, is far as possible from such a con- 
dition. Its channel is partly a ship channel, as already de- 
scribed; and such deep waters are common within Pacific 
barrier reefs. 
The thick coral-made beds reached by artesian borings on 
Oahu (see Appendix), regarded as evidence of the subsidence 
of the island attending their formation, are explained by Mr. 
A. Agassiz on the Murray hypothesis: “the extension sea- 
ward of a growing reef, active only within narrow limits 
near the surface, which was constantly pushing its way sea- 
ward upon the talus formed below the living edge.” ? 
The above considerations may be deemed sufficient to set 
aside the suggestion; for it is only a suggestion, since no 
facts are mentioned in its support. The borings give it none. 
Some of them commence in the elevated reef which is the 
inner part of the fringing reef of the island, within three or 
four hundred yards of the mountain slopes, and go down 
through coral rock interruptedly for two hundred feet or more. 
There is no reason for regarding any part of it talus-made. 
jf. Although no sufficient reason is found for believing in 
talus-made basements, a characteristic by which they might 
be known if lifted into view may be mentioned. The debris 
is laid down on a sloping surface, whence the beds would 
have a corresponding pitch. The deposit would thus differ 
from ordinary coral formations and, too, from all great ex- 
amples of limestone strata of which we have knowledge. In 
1 Bulletin of the Museum of Comparative Zodlogy, 1889, xvii. No. 3. 
