i So 



DISCOVERY REPORTS 



ROCKS FROM MACROBERTSON LAND AND 

 KEMP LAND, ANTARCTICA 



By C. E. TILLEY, B.Sc, Ph.D., F.R.S. 



(Plate XXXVIII; Text-fig.) 



The R.R.S. 'William Scoresby', during its investigations in Antarctic waters in 1936, 

 made landings on the Antarctic coast at Scullin Monolith (MacRobertson Land) 

 and near Sheehan Nunatak (Kemp Land), lying some 160 miles further west. Rock 

 specimens now submitted to the writer for examination were collected from both these 

 points by Mr G. W. Rayner, who has also provided a brief account of their field relations. 



SCULLIN MONOLITH 



In 193 1 the B.A.N.Z. Antarctic Research Expedition made landings on MacRobertson 

 Land at Cape Bruce and at Scullin Monolith, 150 miles further east. Brief descriptions 

 of the rocks collected by this Expedition have already been published. 1 In that collection 

 the locality of Scullin Monolith was represented by two igneous gneisses of granitic 

 composition — quartz-microperthite gneisses carrying garnet, biotite and smoky quartz. 



.Bertha I. 



KEMP 



LAND 



Kf 



Scullin Monolith 



MAC ROBERTSON LAND 



60° 



The ' William Scoresby ' collection comprises about a dozen specimens all of which are 

 of igneous origin and the majority acidic and gneissic in character. The dominant type 

 is a coarse grained quartz microperthite gneiss with garnet and biotite as the chief 

 ferromagnesian constituents. Some of them carry large porphyritic crystals of micro- 

 perthite an inch in length. Primary foliation, which is evident in many of the specimens, 

 is made visible by the orientation and distribution of biotite, and gneissic structure is 

 strikingly displayed in some specimens by bands of dark smoky quartz. In these features 



1 B.A.N. Z.A.R.E. Reports, 1937, Vol. 11, Pt 2, pp. 17-26. 



