Changes of Level In the Pacific Ocean. 245 



eastward 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 be- 

 gan to grow, which is borne out by the features of Kauai 

 shewing a long respite from volcanic action. We conse- 

 quently detect proof of but little subsidence of the islands. 

 Moreover, there are no deep bays ; and, besides, Kauai has a 

 gently sloping coast plain of great extent, with a steep shore 

 acclivity of one to three hundred feet, all tending to prove the 

 smallness of the subsidence. We should therefore conclude 

 that these islands lie near the limits of the subsiding area, 

 and that the change of level was greatest at the western ex- 

 tremity of the range beyond Kauai. 



Marquesas. — The Marquesas are remarkable for their 

 abrupt shores, often inaccessible cliffs, and deep bays. The 

 absence of gentle slopes along the shores, their angular fea- 

 tures, abrupt soundings close alongside the islands, and deep 

 indentations, all bear evidence of subsidence to some extent ; 

 for their features are very similar to those which Kauai, or 

 Tahiti, would present, if buried half its height in the sea, leav- 

 ing only the sharper ridges and peaks out of water. They are 

 situated but five degrees north of the Paumotus, where eighty 

 islands or more have disappeared, including one at least fifty 

 miles in length. There is sufficient evidence that they par- 

 ticipated in the subsidence of the latter, but not to the same 

 extent. They are nearly destitute of coral. 



Gambler or Mangareva Group. — In the southern limits 

 of the Paumotu Archipelago, where, in accordance with the 

 foregoing views, the least depression in that region should 

 have taken place, there are actually, as we have stated, two 

 high islands, Pitcairrts and Gambler s. There is evidence, 

 however, in the extensive barrier about the Gambler s> that this 

 subsidence, although less than further north, w r as by no means 

 of small amount. On page 371, vol. xi., we have estimated 

 it at 1150 feet. These islands, therefore, although towards 

 the limits of the subsiding area, were still far within it. The 

 valley-bays of the Mangareva islets are of great depth, and 

 afford additional evidence of the subsidence. 



Tahitian Islands. — The Tahitian Islands, along with Samoa 



