SUBSIDENCE IN PACIFIC CORAL REGIONS. 279 



far within it. The valley-bays of the islets of the lagoon 

 are of great depth, and afford additional evidence of the 

 subsidence. 



Tahitian Islands. — The Tahitian Islands, along with Samoa 

 and the Feejees, are near the southern limits of the area 

 pointed out. Twenty-five miles to the north of Tahiti, within 

 sight of its peaks, lies the coral island Tetuaroa, a register 

 of subsidence. Tahiti itself, by its barrier reefs, gives evidence 

 oi the same kind of change ; amounting, however, as we have 

 estimated, to a depression of but two hundred and fifty or 

 three hundred feet. The north-western islands of the group 

 iie more within the coral area, and correspondingly, they have 

 \Wder reefs and channels, and deep bays, indicating a greater 

 amount of subsidence. 



Sainoan or Navigator Group. — The island of Upolu has 

 extensive reefs, which in many parts are three-fourths of a 

 mile wide, but no inner channel The subsidence is estimated 

 on page 126, at one or two hundred feet. The volcanic land 

 west of Apia declines with an unbroken gradual slope oi 

 one to three degrees beneath the sea. The absence of a low 

 cliff is probable evidence of a depression, as has been else- 

 where shown- The island of Tutuila has abrupt shores, deep 

 bays, and little coral. It appears probable, therefore, that it 

 has experienced a greater subsidence than Upolu. Yet the 

 central part of Upolu has very similar bays on the north, 

 which would afford apparently the same evidence ; and it is 

 quite possible that the facts indicate a sinking which either 

 preceded the ejections that now cover the eastern and western 

 extremities of Upolu, or accompanied this change of leveL 

 The large island of Savaii, \Ne^?it of Upolu, has small reefs, 

 small because probably of volcanic action ; for it bears, every^ 

 where, evidence of comparatively recent eruption ; from it, 

 therefore, we gather no certain facts bearing on this subject. 

 East of Tutuila is the ^ora/ island^ Rose. It may be, there- 

 fore, that the greatest subsidence in the group was at its 

 eastern extremity. 



Feejee Islands. — We have already remarked upon this group 



