196 DALY. 



shoals, which, arising precipitously, uniformly reach to within a 

 few feet of the surface. It was to me most remarkable that we did not 

 meet wath a single knoll of any sort jutting up to indeterminate 

 depths."^* Gardiner also speaks of the Seychelles bank as "extraor- 

 dinarily level," with depths of from 55 m. to 65 m.; and of "the 

 wonderfully constant depth" of about 60 m. on the great Nazareth 

 bank (Indian ocean). ^^ (See Fig. 18.) 



Among the conclusions reached by Bassett-Smith after his long 

 study of the Macclesfield bank, one reads: "The evenness of depth 

 is the most striking feature of the chart." ^^ (See Figs. 19-20.) 



Wharton, one of the leading experts on oceanic bathometry, writes 

 concerning large banks southwest and south of the Ellice islands: 

 "The remarkable thing about these banks is the absolute uniformity 

 of the depth of water over their areas, inside the low rim of growing 

 coral which encircles their edges in \arious degree. This depth is 24 to 

 26 fathoms." (See Figs. 34 A and 34B.) In the same article he adds: 

 " I have no hesitation in saying that a flat floor is an invariable char- 

 acteristic of a large atoll and I cannot find his [Darwin's] 'deeply 

 concave surface' in any large atoll. On the contrary, a flat surface is 

 found in all these, whether the rim be above, or below the surface." ^^ 

 Wharton explained the flatness by wave-cutting, with the sea surface 

 at its present level, though he did not show why such abrasion was 

 once possible, while the defending reefs now make it largely impossible. 

 Notwithstanding the incompleteness of his theory of coral reefs, 

 Wharton's choice of the agency which produced the flatness of lagoon 

 floors and of banks seems irresistible. He rightly regarded this flat- 

 ness as no less than fatal to the Darwin-Dana theor3^ (See page 240.) 



Cross sections of the Australian shelf, illustrating the superimposition of the 

 existing coral reefs on a broad platform, which was developed before, and 

 independently of, the growth of those reefs. 



Figure 21. At 13° 10' S. Lat., through the Great Barrier Reef. 



Figure 22. At 16° ;35' S. Lat., through the Great Barrier Reef. 



Figure 23. At 24° 30' S. Lat., outside the coral sea. 



Figure 24. At 25° 45' S. Lat., outside the coral sea. 



The shallowness of the shelf at 24° 30' S. Lat. is explained by Recent, rapid 

 aggradation due to the local configuration of the coast, and by a corresponding, 

 special abundance of sand. Depths in fathoms. Uniform scales; vertical scale 

 12 times the horizontal. Water shown in black; rocks, including reefs, are 

 lined. 



34 J. S. Gardiner, The Fauna and Geography of the Maldive and Laccadive 

 Archipelagoes, Cambridge, England, 1, 9 (1903). 



35 ,1. S. Gardiner, Geog. Jour.. 28, 330 (1906) ; Nature, Nov. 9, p. 44 (1905). 



36 P. W. Bassett-Smith in Report on Dredgings obtained on Macclesfield 

 Bank, etc., Hydrographic Office, Adrairaltv, London, 1894. 



37 W. J. L. Wharton. Nature, 55, 390 (4S97). 



