38 PHYSIOGRAPHIC GEOLOGY. 



forming its eastern extremity ; westward there are the Samoan (5) and 

 Gilbert (8) groups, and others intermediate ; still northwestward there are 

 the Kadack and Ralick groups (9, 10), and in 20° N., on the same line. 

 Wakes Island. 



(a) The chain, as is seen, consists of a series of parallel ranges, suc- 

 ceedinp- and overlapping along the general course, in the manner illustrated 

 on page 28, when speaking of mountains, (b) It varies its course gradually 

 from west-northwest at the eastern extremity to north-northwest at the 

 western, (c) Its mean trend is northwest-by-west (N. 56° W.), the mean 

 trend of all the groups of the northwesterly system in the ocean, (d) The 

 chain is a curving chain, convex to the southward, and marks the position of 

 a great central elliptical basin of the Pacific having the same northwesterly 

 trend. The Hawaiian is on the opposite side of it, slightly convex to the 

 north. 



The Marquesan range (12, Fig. 24) lies in the same line with the Fanning group (13) 

 to the northwest, just north of the equator ; and, if a connection exists, another great 

 chain is indicated, — a Marquesan chain. 



Australasian chain (Fig. 25). — New Hebrides (K) and New Cale- 

 donia (M) belong to the Australasian island chain. The line of New 

 Hebrides is continued northwestward in the Solomon group (I) and New 

 Ireland, though bending a little more to the westward, and terminates in 

 Admiralty land (Gr), near 145° E., where it becomes very nearly east-and- 

 west : the length of the range is about 2000 miles. Taking another range 

 in the chain, New Caledonia (M), the course is continued in the Louisiade 

 group (H) ; then the north side of New Guinea (E), which continues bend- 

 ing gradually till it becomes east-and-west, near 135° E. In the southeast, 

 belonging to the same general line, there is the foot of the New Zealand boot 

 (0). The coral islands between New Caledonia and Australia appear also 

 to be other lines in the chain. 



From New Guinea (E, F), the east-and-west course is taken up by Ceram 

 (D), and again, more to the south, in the Java line of islands (A, B, C) ; 

 and from Java (B) the chain again begins to rise northward, becoming north- 

 west finally in Sumatra (A) and Malacca. 



The several ranges make up one grand island chain, with a double curva- 

 ture, the whole nearly 6000 miles long. In Fig. 25, a line stands for each 

 group, and indicates its course ; it shows the composite nature of the chain, 

 and the curving course, in connection with a prevailing conformity to a 

 northwesterly trend. 



Blending of the Australasian and Polynesian island chains. — The two 

 chains blend with one another in the region of the Carolines, Fig. 24 (11). 

 This large archipelago properly includes the Ealick and Radack groups 

 Fig. 24 (9, 10). At the Gilbert group. Fig. 24 (8), the Polynesian chain 

 divides into two parts, — the Ralick and Radack ranges. But the main 

 body of the Archipelago, Fig. 24 (11), trends off to the westward, and is a 



