208 DALY. 



and others, the Recent elevation of many of the Lau islands in the Fiji 

 group has been established. The main Fiji islands and some of their 

 neighbors are not reported to show evidence of general uplift as late 

 as post-Pliocene. Such islands, nearly or quite stable in recent 

 time, are Viti Levu (north and east sides), Vanua Levu, Mbengha 

 (Fig. 32), Ngau, Wakaya, Makongai, Thikombia, Taviuni, lambu, 

 Namuku, Vanua Mblavau, and the Argo cluster. All of these have 

 well defined, coral-crowned shelves at depths averaging about 30 

 fathoms or 55 m. below sea-level. The contrast with the many 

 recently uplifted islands of the same archipelago, named in Table 

 III, is striking. 



Differential movements are recorded at Neu-Lauenburg (Dahl), 

 Buka (Frederici and Sapper), Uvea of the Loyalty group (Davis. 

 See Fig. 30), Vavau (Lister. See Fig. 29), Timor (Molengraaff), and 

 the islands off California (Lawson and W. S. T. Smith). Many other 

 cases must be represented in the table but have not been definitely 

 described. Li the Vavau group Lister states that the recent movement 

 has been upward on the north and downward on the south. The 

 present submarine topography is therefore significant. A wide shelf, 

 locally covered with 70 fathoms (128 m.), or more, of water has been 

 found to the south of the group; while a marked bench is absent on 

 the north (Fig. 29). 



Off the California coast, San Clemente island, raised in Post- 

 Pliocene time, has a magnificent series of elevated benches but lacks 

 an encircling submarine shelf. The neighboring island of Santa 

 Catalina, contemporaneously sunken, has a marked shelf, from L5 to 

 6.5 km. wide and covered with water reaching 65 fathoms (119 m.) 

 in depth.^^ 



Inspection of the charts shows oceanic islands outside of the coral 

 seas to have submarine shelves at depths of from 45 m. to 80 m., if 

 those islands have not undergone Recent crustal movement. The 

 presence or absence of such a shelf may, indeed, afford a criterion of 

 Recent uplift. The fact that the Falkland islands have a broad shelf 

 at 55-90 m. suggests that Halle is right in discrediting post-Glacial 

 elevation for that region. ■*" 



Incomplete as it is, the evidence so far published seems to warrant 

 the following statements, (a) The undisturbed tropical islands have 



39 A. C. Lawson, Bull. Dep. Geol., Univ. California, 1, 128 (1893); W. S. T. 

 Smith, ibid., 2, 179 (1900\ and 18th Ann. Rep., U. S. Geol. Survey, Part 2. 

 p. 46.5 (1898). 



40 T. G. Halle, Bull. Geol. Inst.. Univ. Uppsala, 11, 222 (1912). 



