THE OCEANIC CORAL-ISLAND SUBSIDENCE. 40] 
The absence from the American coast of the Atlantic, 
of any coral reefs in the Cretaceous beds, and of any reef corals, 
seem to show that the oceanic temperature off this coast was 
not favorable for such corals; and if so, then the line of 68° | 
F’. extended at least 20° farther north on the European side! 
of the ocean, than on the Atlantic—an inequality to be ac- 
counted for in part by the existence of the Gulf Stream. But, 
in addition, the whole range of life in the European Creta- 
ceous, and its vastly greater variety of species, leave no doubt} 
as to the higher temperature of the ocean along its European 
border; so that the idea of a Cretaceous Gulf Stream must be 
accepted. And that of a Tertiary is demonstrated by similar 
facts. 
If the Gulf Stream had its present position and force in 
Odlitic, Cretaceous and Tertiary times, then the ocean had, 
throughout these eras, its present extension and oceanic char- 
acter; and, further, no barrier of land extended across from 
South America to the Canaries and Africa, dividing the South 
from the North Atlantic, but all was one great ocean. | 
Such a barrier would not annul entirely the flow of the Gulf 
Stream; yet the North Atlantic is so small an ocean, that if 
left to itself, its system of currents would be very feeble. 
XIV. THE OCEANIC CORAL ISLAND SUBSIDENCE. 
Coral islands have been shown to be literally monuments 
erected over departed lands; and, through the evidence from 
such records, it is discovered that the Pacific has its deep-water 
mountain chains, or lines of volcanic summits, not merely 
hundreds, but thousands of miles in leneth. Some of the 
ranges of high islands are proved by such records to have an 
under-water prolongation, longer than that above water: the 
Hawaian Islands for example, which have a length of only 
