836 THE PETROLOGY OF SOUTH GEORGIA. 



DESCRIPTION OF PLATE XCIV. 



Fig. 1. x 8. Banded arenaceoua slate, showing strain-slip in argillaceous bands associated with folding in the 



arenaceous bands. Lower Division, Cumberland Bay Series, Royal Bay, South Georgia. 

 Fig. 2. x 44. Radiolaria in fine, muddy tuff. Middle Division, Cumberland Bay Series, Leith Harbour, 

 South Georgia. 



The radiolaria are now represented by white spherical bodies consisting of cryptocrystalline silica. 

 Fig. 3. x 21. Crystal tuff, Lower Division, Cumberland Bay Series, Port Gladstone, South Georgia. 



This consists of clear fragments of fresh orthoclase and dark chips of trachyte in about equal pro- 

 portions, embedded in a scanty indeterminate gronndmass. 

 Fig. 4. x 8. Coarse tuff or agglomerate. Middle Division, Cumberland Bay Series, Cumberland Bay, 

 South Georgia. 



This differs from the above in containing much larger fragments of trachyte. 

 Fig. 5. x 12. Granite-porphyry, loose block in Moraine Fiord, Cumberland Bay, South Georgia. 



This rock shows sericitised phenocrysts of felspar and chloritised hornblende and biotite, in a 

 quartzose microcrystalline gronndmass. 

 Fig. 6. x 12. Ophitic diabase, intrusive in Lower Division, Cumberland Bay Series, Royal Bay, 

 South Georgia. 



The rock is much decomposed, and consists of altered felspar laths (dark in slide), penetrating 

 large areas of colourless augite. 



