Notices of Memoirs — Papers read at British Association. 35 



Orthis personata, Zeill. 

 Orthis vulvaria, Schl. 

 Orthis circidaris, Sow. 

 Spirifer primcsvus, Stein. 

 S-pirifer subcuspidatus, Schnur. 

 Spirifer cf. hystericus, Schl. 



Crinoid columnars, some very large, f inch across. B.M., 

 E 14062. 

 The Zodanella, which was obtained by the last drive of the crow- 

 bar, is magnificent and quite equal to the type-specimen. 



It is hoped that these lists will stir up others to search for fossils 

 in this interesting area. We are much indebted to Mr. G. C. Crick 

 and Mr. W. D. Lang, who have most carefully examined and helped 

 us with some of our material. 



inTOTigibs OIF Dvi::E3:vnoiies, ieito. 



British Association for the Advancement of Science. 

 Meeting in South Africa, August 15th to Sept. 1st, 1905. 

 Papers read before Section C, Geology, 



I. — On the Eelation between Ore Veins and Pegmatites. 

 By Professor E. Beck. 



ri^HE author gave a summary of the latest investigations on the 

 |_ origin of pegmatites, by W. C. Brogger, H. Eosenbusch, 

 S. Arrhenius, J. H. L. Vogt, U. Grubenmann, and others. In 

 conformity with these authors, he explained pegmatites as products 

 of crystallisation from the superheated water, which remained, after 

 the consolidation of a plutonic magma, as a concentrated solution 

 containing many of the rarer chemical elements and compounds 

 formerly distributed through the whole fluid mass. Being retained 

 in the depths of a plutonic focus under high pressure, these remains 

 of magmatic water could pass through a very gradual process of 

 cooling; whereas the so-called 'juvenile' thermal waters (Juvenile 

 Quellen) of similar origin found their way to the upper parts of the 

 earth's crust, and caused there the formation of minerals at lower 

 temperatures and pressures. 



Most ore veins belong to the second class, but a considerable 

 number of occurrences may be styled metalliferous pegmatites. 



The best known examples of these are found in the group of tin 

 ores, and as such were discussed the ore veins of Zimwald, Graupen, 

 Embabaan, and others. 



As examples of copper ores were cited those of Telemarken in 

 Norway ; and finally some gold-bearing quartz reefs were described 

 which are very nearly related to pegmatites, and that not merely 

 by their characteristic mineralogical composition (Berezowsk, 

 Southern Appalachians, Yukon District, Passagem, and other 

 instances in Brazil). It may be mentioned in proof of this that 

 certain gold quartzes contain tourmaline, the characteristic mineral 

 of all pegmatites. 



