360 CORALS AND CORAL ISLANDS. 
destitute of islands, about longitude 170° to 175° W., and 
latitude 8° to 10° N. 
But we may derive some additional knowledge respecting 
this area of subsidence from other facts. 
Hawauan Range.— We observe that the western islands 
in the Hawaiian Range, beyond Bird Island, are atolls, and all 
indicate a large participation in this subsidence. To the east- 
ward in the range, Kauai and Oahu have only fringing reefs, 
yet in some places these reefs are half a mile to three fourths 
in width. They indicate a long period since they began to 
grow, which is borne out by the features of Kauai showing a 
long respite from volcanic action. We detect proof of sub- 
sidence, but not of a large amount. Moreover, there are no 
deep bays; and, besides, Kauai has a gently-slopime coast 
plain of great extent, with a steep shore acclivity of one to 
three hundred feet. The facts favor the idea of much less 
subsidence since the time when the corals began to grow in 
the region of Kauai and Oahu than along the range to the 
westward. The rather small width of the reefs about these 
two islands may be owing to the former action of their vol- 
canoes, which may have been burning during the earlier part 
of the coral-reef era. But deep-sea soundings must be made 
along the whole chain, including the line to the westward, 
before we can speak positively about the change of level. 
The western islands of the range bear some evidence of 
having, in recent times, commenced a new subsidence after a 
temporary cessation. They all have little dry land and vege- 
tation about the reefs. Brooks’s Island, in latitude 28° 15'N., 
— 
and longitude 177° 20’ W., eighteen miles in circumference, 
has on its north and east sides a compact coral wall of about 
five feet elevation, which continues for four and a quarter 
miles, and then becomes a line of detached rocks at tide level. 
