( 797 ) 



XXIII. — Geological Observations in South Georgia. By D. Ferguson, Mem. Inst. M.E. 

 F.R.G.S. Communicated by Professor J. W. Gregory, D.Sc, F.R.S. 



(MS. received March 2, 1914. Read July 6, 1914. Issued separately May 20, 1915.) 



[Plates LXXXI-XCL] 



CONTENTS. 



Introductory .... 

 South Georgia : Position of the Island 

 Physical Character of South Georgia 

 Previous Geological Literature 

 The Rocks of South Georgia . 

 Local Distribution of Rocks . 



797 

 797 

 798 

 800 

 802 

 805 



The Geological Age of the Rocks of South Georgia 812 



Concluding Observations 813 



Explanation of the Plates 813 



Appendix on the Physiography. By Professor 



Gregory 814 



Introductory. 



In the investigation of a remote and isolated island for mineral and metalliferous 

 deposits its geological structure and the character of the rock masses of which it is 

 formed are of primary importance. Where the evidences of metalliferous deposits 

 are more or less openly and widely exposed the geological structure, while still of 

 interest, is not so important. Ore deposits, as a rule, occur in rock-bodies which 

 have definite relations to each other, a characteristic geological structure. 



In the island of South Georgia, where the exposed evidences of metalliferous 

 ores are very slight, the investigation of its rock-bodies, their character and 

 geological structure, is a necessity. By making an examination of that kind, we 

 endeavour to ascertain if there may be concealed ore-bodies which further exploratory 

 prospecting may with a reasonable probability expose to view. Where the peculiar 

 types of geological structure generally identified with metalliferous ore-bodies are 

 not sufficiently developed, only small and scattered ore deposits can be reasonably 

 anticipated. The presence of metalliferous ores in an indefinite form over any area 

 under investigation necessitates a more detailed examination of it, in order that no 

 evidence bearing on their possible occurrence may be omitted. The island of South 

 Georgia is an area of that kind, and the prospecting work undertaken there was 

 conducted in conformity with that opinion. 



South Georgia : Position of the Island. 



The island of South Georgia occupies one of the corners of an irregular four- 

 sided figure, while the Falkland Islands, the South Orkney Islands, and the South 



TRANS, ROY. SOC. EDIN., VOL. L, PART IV (NO. 23). 



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