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THE EOCKS OF TEISTAN D'ACUNHA, BEOUGHT BACK 

 • BY H.M.S. ODIN, 1904, WITH THEIE BEAEING ON 

 THE QUESTION OF THE PEEMANENCE OF OCEAN 

 BASINS. 



By E. H. L. Schwarz, A.E.C.S., F.G.S. 

 (Bead October 26, 1904.) 



Introduction — Description of the Tristan d'Acunha group : — Tristan d'Acunha, 

 Inaccessible Island, Nightingale Island, Stoltenkoff Island, Middle Island 

 — Source of the specimens described — The importance of the study of 

 Oceanic Islands — Does the level of the sea rise or the land sink ? — The 

 Agulhas Bank and Continental shelf s — Other Oceanic Islands, Atlantic : — 

 Falkland Islands — The land connection between Africa and South America : 

 — In Devonian Times, In Jurassic Times, In Later Times — The revelations 

 of the pendulum — Other Oceanic Islands, Atlantic: — St. Paul's Bocks, 

 Ascension, Mayo, Cape Verde Islands, Canary Islands, Gaussberg, South 

 Georgia, Kockall Island, The Antilles — Legendary Islands : — Atlantis, 

 Antilla, Brasil, St. Brandan's Island —Other Oceanic Islands, Pacific : — 

 New Caledonia, Fiji Islands, Solomon Islands, New Hebrides, Tonga or 

 Friendly Archipelago — N on -volcanic material brought up in volcanic 

 eruptions : — Italy, Germany, Scotland, South Africa — The heat of volcanic 

 eruptions : — Luzi's experiments in diamonds, Chaper's views on the South 

 African diamond mines — Quartz sand in mid-Atlantic probably due to a 

 cold volcanic eruption : — Sir A. Geikie's evidence from Scotland, Branco's 

 evidence from Swabia — The heat of volcanic eruptions : — Kimberlite in 

 Borneo, Australia, and Sutherland, Cape Colony, Agglomerate necks in the 

 Drakensberg — The Cave Sandstone: — The Cave Sandstone, a variety of tuff, 

 Similar rocks in Ascension, Peperino the same kind of material as the Cave 

 Sandstone, The Cave Sandstone poured out as a mud, The Tonga tuffs — 

 Beview of the evidence in favour of volcanic islands standing on a continental 

 base — Volcanoes not confined to ejecting molten material — The South African 

 evidence for the theory that volcanoes are due to crustal friction : — The 

 Bushveld amygdaloid, The Baviaan's Kloof crush-breccia, The Drakensberg 

 volcanoes, The Sutherland volcanoes — The Sutherland and Griqualand West 

 volcanoes: — The sinking of the Karroo basin, The intrusion of the dolerite, 

 The effect of the heated material on the sedimentary rocks, The formation of 

 the folded mountain ranges in the south of the Cape Colony, The production 

 of shearing in the north of the Cape Colony, The volcanic pipes due to the 

 heat produced by the shearing motion — Tristan d'Acunha rocks show the 

 nature of the underlying ridge to be continental— The evidence of the South 



