AGE OF MAN. 587 



In Greenland a slow subsidence is taking place. For 600 miles 

 from Disco Bay, near 69° N., to the Firth of Igaliko, 00° 43', the 

 coast has been sinking for four centuries past. Old buildings and 

 islands have been submerged, and the Moravian settlers have had 

 to put down new poles for their boats, and the old ones stand, Lyell 

 observes, " as silent witnesses of the change. " 



On the North American coast south of Greenland, along the 

 coasts from Labrador to New Jersey, it is supposed that similar 

 changes are going on ; though more investigation is required to esta- 

 blish fully the fact. G. H. Cook concludes from his observations 

 that a slow elevation is in progress along the coast of New Jersey, 

 Long Island, and Martha's Vineyard (Am. Jour. Sci. [2] xxiv. 

 341) ; and, according to A. Gesner, the land is rising at St. John's 

 in New Brunswick ; sinking at the island of Grand Manan ; rising 

 on the coast opposite, at Bathurst ; sinking near the Bay of Fundy 

 and Basin of Mines in Nova Scotia, except, perhaps, on the south 

 side, and rising at Prince Edward's Island. 



The Coral Islands of the Pacific are proofs of a great secular 

 subsidence in that ocean. The line C C C (Physiographic Chart) 

 between Pitcairn's Island and the Pelews divides coral islands from 

 those not coral ; over the area north of it to the Hawaian Islands all 

 the islands are atolls, excepting the Marquesas and three or four 

 of the Carolines. If then the atolls, as will be shown on a future 

 page, are registers of subsidence, a vast area has partaken in it, — 

 measuring 6000 miles in length (a fourth of the earth's circum- 

 ference) and 1000 to 2000 in breadth. Just south of the line there 

 are extensive coral reefs ; north of it the atolls are large, but they 

 diminish towards the equator and disappear mostly north of it ; 

 and as the smaller atolls indicate the greater amount of subsidence, 

 and the absence of islands still more, the line A A may be regarded 

 as the axial line of this great Pacific subsidence. The amount of 

 this subsidence may be inferred, from the soundings near some of 

 the islands, to be at least 3000 feet. But as two hundred islands 

 have disappeared, and it is probable that some among them were 

 at least as high as the average of existing high islands, the whole 

 subsidence cannot be less than 6000 feet. It is probable that this 

 sinking began in the Post-tertiary period. 



Since this subsidence ceased — for the wooded condition of the 

 islands is proof of its having ceased — there have been several cases 

 of isolated elevations. The following are some of the islands that 

 have been elevated: — Oahu (Hawaian Islands), 25 feet; Elizabeth 

 Island, Paumotu Archipelago, 80 feet ; Metia or Aurora, 250 feet ; 

 Atiu, Hervey Group, 12 feet; Mangaia, 300 feet; Eurutu, 150 feet; 



