Xli PEOCEEDINGS OP THE GEOLOGICAL SOCIETY. [vol. lxxix, 



collected liis specimens under difficulties and on very rapid traverses, 

 they were all accurately localized. With the exception of some 

 of the specimens collected on Gough I. by the Scotia Expedition, 

 earlier descriptions of rocks from these islands were based on 

 pebbles or poorly-localized specimens. As a result of the Quest 

 Expedition nearly all the types recorded had now been found in 

 place, and there would be sufficient material available for analysis. 

 The rock collected on Rowett's Peak (on Gough I.) proved to be 

 an essexite. ' The Apostle ' was formed of aegirine-trachyte con- 

 taining a problematical mineral (described by Dr. Campbell), 

 believed by the speaker to be an iron-rich member of the olivine 

 group. The rocks of the Tristan da Cunha Group included basalts 

 and bornblende-bearing trachy-basalts, with trachytic lavas on 

 Nightingale and Middle Islands. The rock described by 

 A. Penard as ' bronzite-andesite ' had been found in situ, and 

 the ' bronzite ' appeared to be an olivine similar to that found in 

 the trachyte of ' The Apostle ' on Gough Island. 



Mr. J. M. Woedie remarked that the rocks from Elephant I. 

 were of the same nature as the few specimens collected by the 

 shipwrecked Endurance party in 1916, and the island may, there- 

 fore, be regarded as composed throughout of crystalline schists in 

 different degrees of metamorphism. The Lecturer's work on 

 South Georgia would undoubtedly help to elucidate some of the 

 numerous problems presented by that island. Although only one 

 fossil was unearthed, its importance was considerable, for it in- 

 creased the probability that the Cumberland Bay Series is of 

 Mesozoic, rather than of Paleozoic, age. The Lecturer appeared 

 to have had the same difficulty in accepting Mr. Ferguson's inter- 

 pretation of the tectonics and stratigraphy as the speaker himself 

 felt in 1914. It is very doubtful whether there are any uncon- 

 formities in South Georgia. The Lecturer had cited a case with 

 some evidence of one ; but, in view of the identity of strikes and 

 of rock-types, would not reversed faults and very sharp folds 

 explain the conditions more easily? Folds of this nature were 

 very obvious in some of the excellent photographs which the 

 Lecturer had shown on the screen. 



Prof. W. T. Goedox said that the Lecturer had referred to a 

 plant petrifaction from South Georgia which the speaker was per- 

 mitted to examine. The specimen was very imperfectly preserved, 

 for each cell had been disintegrated to such an extent that 

 only the outline remained. Yet, small as were the fragments, 

 they were sufficiently large to allow of differentiation into pith 

 and secondary wood. The wood could be proved to belong to 

 the type Araucarioxylon, and the minute structure of the pits on 

 the cell-walls of the wood favoured a Mesozoic, rather than a 

 Palaeozoic, age for the specimen. It was impossible, on account 

 of the poor preservation of the plant, to say whether it could be 

 correlated with Antarcti coxy Ion, and therefore with the Triassic 

 genus Mhexoxylon from South Africa. The balance of the 

 characters seemed to incline towards a Mesozoic age for the beds. 



