IV.—Pipe-Amygdaloids

Extract

Pipe-Amygdaloids, although recorded in the Deccan Traps of India and in Tertiary Basalts from Mull, are rather uncommon, rocks except in South Africa. They were described by Professor E. Cohen, who obtained his specimens through Mr. J. Orpen from the Stormberg lavas (Lower Jurassic) of Basutoland, a formation in which they are very abundant. Since then they have been found in other volcanic formations, e.g., in the very ancient lavas of the Ventersdorp System in the Divisions of Kimberley and Barkly West, in the Bushveld Amygdaloid of the Transvaal and the Basalts of the Lebombo and Zululand (which all overlie rocks belonging to the Karroo System), and in the volcanic fissure of the Zuurberg in the Cape Colony (probably of post-Neocomian age). They have a striking resemblance to organic structures, and Cohen likens them to certain corals; in some exposures of lava the little pencils of white zeolite studding the surface remind one of the casts of worm burrows.