PERMANENCE OF OCEAN BASINS 
277 
of oceans and continents is the supposed absence of abysmal 
deposits on any existing land surface. The discovery, how¬ 
ever, of true deep-sea ooze in Barbados and Cuba shows that 
this argument is no longer valid.* There only remains one 
other argument in favour of this theory, and that is the 
structure of the oceanic islands. With two exceptions, re¬ 
marks Dr. Wallace, they do not contain any Mesozoic or 
Palaeozoic rocks, being mostly volcanic. Hence he concludes 
that these islands must be of modern origin. How illusive 
this conception is may he gathered from Dr. Blanford’sf re¬ 
marks on this subject: “ If Africa, south of the Atlas, sub¬ 
sided 2,000 fathoms, what would remain above water? So 
far as pur present knowledge goes, the remaining islands 
would consist of four volcanic peaks, the Camaroons, Mount 
Kenia, Kilimanjaro, and Stanley’s last discovery, Ruwenzori, 
together with an island, or more than one, containing part of 
the Abyssinian tableland, which, like the others, would be 
composed of volcanic rocks, but, unlike them, would consist of 
horizontal or nearly horizontal lava flows, probably of 
of Mesozoic age. In southern Africa, too, the peaks of the 
Stormberg and Drakensberg, though not rising, or scarcely 
rising above 10,000 feet, are the highest in the country and 
consist of volcanic rocks. The same is the case with the 
highest peaks in Madagascar, in Mexico, in the Caucasus, in 
the Elbruz chain south of the Caspian, and in many other 
parts of the world; though the case of Africa is perhaps 
the most remarkable.” 
The question whether all the numerous oceanic islands that 
are scattered about the Pacific and Atlantic Oceans are really 
modern volcanic products or of recent organic origin, has 
also received some attention recently. According to Dr. 
Arldt-,$ Archaean rocks have been noticed on the Solomon 
islands, gneiss and allied rocks occur on the New Hebrides 
and Now Caledonia, while even from the Marquesas have 
been recorded ancient rocks. 
So far I have discussed only a very small portion of the 
purely zoological aspect of the trans-Atlantic land connection 
* Gregory, J. W., “Geology of the West Indies,” p. 307. 
t Blanford, W. T., “ Anniversary Address,” pp. 34—35. 
| Arldt, Th., “ Entwieklung der Ivontinente,” pp. 457—458. 
