4()2 CORALS AND CORAL ISLANDS. 
four hundred miles from Hawaii to Kauai, and five hundred 
and thirty to Bird Island, the western rocky islet of the group, 
stretch on westward, as the coral registers show, even to a dis- 
tance of two thousand miles from Hawaii, or, as far as from 
New York to Salt Lake City; and how much farther is un- 
known, as the line of coral islands here passes the boundary 
of the coral reef seas, or the region where coral records are 
possible. 
Other ranges of submerged summits are shown to extend 
through the whole central Pacific, even where not a rocky 
peak remains above the surface; for all the coral islands from 
the eastern Paumotus to Wakes’ Island, near long. 170° E,. 
and lat. 19° N., north of the Ralick and Radack (or Marshall) 
groups, are in linear ranges; and they have, along with the 
equally linear ranges of high islands just south, a nearly uni- 
form trend, curving into northwest and north-northwest at the 
western extremity. The coral islands consequently cap the sum- 
mits of linear ranges of elevations, and all these linear ranges 
together constitute a grand chain of heights, the whole over five 
thousand miles in length. Thus, the coral islands are records 
of the earth’s submarine orography, as well as of slow changes 
of level in the ocean’s bottom. 
This coral island subsidence is an example of one of the 
great secular movements of the earth’s crust. ‘The axis of the 
subsiding area—the position of which is stated on page 363, 
has a length of more than six thousand miles—equal to one- 
quarter of the circumference of the globe; and the breadth, 
reckoning only from the Sandwich Islands to the Friendly 
Group (or to Tongatabu) is over twenty-five hundred miles, 
thus equalling the width of the North American continent. 
A movement of such extent, involving so large a part of the 
earth’s crust, could not have been a local change of level, but 
Se 
