LAND CONNECTION BETWEEN AFRICA AND AMERICA 83 



in the other, yet the work of v. Drygalski^ shows that there are 

 factors which render both to a certain extent reconcilable. A great 

 advance will have been made if it can be sufficiently proved that 

 there was once a land surface where now the Atlantic Ocean or 

 some notable part of it, lies ; and I will now present the arguments 

 n favor of this view. ^ 



Evidence from Ascension Island. — Ascension Island, like the 

 Tristan group and St. Paul's rocks, lies in the mid-Atlantic ridge. 

 Composed chiefly of volcanic rocks, there are abundant traces of 

 the substructure being granitic in nature. Darwin states that in 

 the neighborhood of the Green Mountain fragments of extraneous 

 rocks are frequently met with imbedded in the midst of scoriae.^ 

 Professor Renard confirms this, and mentions as occurring in this 

 manner, granite, granitite, diabase, and gabbro, "torn up from 

 the depths by eruptions."^ There is no record of the granite basis 

 appearing above the water-line; but if one takes these observations 

 and considers them in the hght that Woolnough has thrown on 

 the Fiji Islands, another group which until recently had been 

 thought to be purely volcanic, the true significance of these ejected 

 blocks is made clear. In Fiji, Woolnough found that the whole 

 group was underlain by a basis consisting of granite, quartz-diorite, 

 quartzite, slates, and old sedimentary rocks of an indeterminate 

 age, 4 and I confidently look to the results of his second expedition 

 for affording still more striking evidence for the continental origin 

 of these islands. 



Evidence from St. Paul's rocks. — A great deal has been written 

 on the ultra-basic rocks from this small mass of land in mid-ocean, 

 and the opinions as to whether they are igneous or metamorphic 

 have been equally balanced. The deformation of crystals im- 

 bedded in the matrix is such, however, that we must assume 

 that the rock has been subjected to earth-movements, and in spite 

 of the islands lying in a region of active submarine volcanic action, 

 such a careful author as Neumayr was satisfied that this ultra-basic 



1 Zeitschrift der Gesellschajt fur Erdkunde (Berlin, 1887). 



2 Geological Observations on Volcanic Islands, 1851, p. 40. 



3 Challenger Reports, Physics and Chemistry, Vol. II, Part 7, p. 62. 



• * Proceedings of the Linnean Society of New South Wales, 1903, Part 3. 



