32 



PHYSIOGRAPHIC GEOLOGY. 



the north, in tho same line, near 30° S., lie the Kermadec Islands, and 

 farther north, near 20° S., the Tonga or Friendly Islands. 



The Ladrones, north of the equator, follow the same general course. 

 It also occurs in many groups of the northwesterly system character- 

 izing subordinate parts of those groups. Thus, the westernmost of 

 the Hawaian Islands, Nihau, lies in a north-northeast line, and the 

 two lofty peaks of Hawaii have almost the same bearing. 



Pacific island-chains. — The groups of Pacific islands, with a 

 few exceptions, arc not independent lines, but subordinate parts of 

 island-chains. There are three great island-chains in the ocean 

 which belong to the northwesterly system, — The Hawaian, the Poly- 

 nesian, and the Australasian, — and, excluding the Ladrones, which 

 pertain to the western Pacific, one belonging to the northeasterly sys- 

 tem, viz. : the Tongan or New Zealand chain. 



(1.) Hawaian chain. — This chain has already been described. 



(2.) Polynesian chain. — This chain sweeps through the centre of 

 the ocean, and has a length of 5,500 miles, or nearly one fourth the 

 circumference of the globe. (See Fig. 27.) The Paumotu Archipel- 

 ago (1), and the Tahitian, Eurutu, and Hervey Islands (2, 3, 4) are 

 parallel lines in the chain, forming its eastern extremity ; westward 





Fig. 27. 





A 



V 





\\ \ 10 







9 \\ 



\X 





h "'■•-- "' \ 



\ 





a 



"""■'^. 





1 to 10, the Polynesian chain : 1, Paumotu group ; 2, Tahitian ; 3, Rurutu group ; 4, Hervey 

 group; 5, Samoan, or Navigators'; 6, Vakaafo group; 7, Vaitupu group; 8. Gilbert's 

 group ; 9, Ralick ; 10, Radack ; 11, Carolines ; 12, Marquesas ; 13, Fanning group ; 14, 

 Hawa'an. a to fy, part of the Australasian chain: a, New Caledonia; b. Loyalty group; 

 c, New Hebrides ; d, Santa Crua group ; e, Salomon Islands ; /, Louisiade group ; g, New 

 Ireland ; A, Admiralty group. 



