CAPE BARNE 219 



very glassy, and, besides these, other phenocrysts are met with in the form of leucite 

 in small rounded isotropic crystals, and of olivine of a yellow variety in small rounded 

 grains. 



Cape Barne. As shown on the detailed geological map of the Cape Royds to 

 Cape Barne area we found developed at Cape Barne an elongated mass of basalt and 

 basalt agglomerate. Its general trend is east and west, inclining to north-west 

 at its western extremity on the coast. As shown on the section on line A to C 

 this basaltic belt is strongly intrusive into the older kenyte lavas, large blocks of 

 kenyte with reddened crystals of anorthoclase being enclosed in the scoriaceous 

 basalt of Cape Barne. A section of this is shown on the detailed geological map of 

 this area. 



Notes on Cape Barne Lavas. The Cape Barne area is bounded on the west by 

 the sea, to the south by the Cape Barne Glacier, to the east by the foothills and 

 snow slopes of Erebus, and to the north by a shrunken glacier to the east of Back- 

 door Bay, Cape Royds. 



The most westerly point of the Cape is Cape Barne Pillar, a rounded plug of 

 basaltic agglomerate 150 feet high. Evidently this mass formed originally part of 

 the material choking the neck of a small volcano. Across the middle of this plug, 

 striking almost north and south, runs a dyke of a very highly-jointed basalt, the 

 strengthening influence of which probably played a great part in enabling the Pillar 

 to resist the denudation which has already worn down and removed the greater part 

 of the volcano. 



To the east of the Pillar is a steep sugarloaf-shaped hill, representing apparently 

 all that is left of the volcano. This hill is composed mainly of steeply-sloping tuffs, 

 generally fairly coarse and agglomeratic, but with bands of finer material. Inter- 

 calated amongst the tuffs are one or two thin flows of highly-jointed basalt. So 

 highly jointed were they, that on our earlier visits we failed to distinguish them 

 from the agglomeratic beds above and below them. 



The larger materials of the agglomerates were mostly fragments of basalt or of 

 basaltic agglomerate, but several burnt and reddened fragments of kenyte were 

 lying at the foot of the hill amongst the debris, and on one occasion one of these 

 kenyte fragments was found in place cemented in the agglomerate. The ice-foot 

 below the sugarloaf-shaped hill after a southerly wind would be strewed with debris 

 dislodged from the hill sides, and it was from amongst this debris that two or three 

 pieces of vesicular basalt were picked, with vesicles up to three-eighths of an inch 

 in diameter filled with very pure sulphur. 



Farther inland from the Cape are dome-shaped, obviously glaciated, hills, 

 composed, as far as could be seen through the mask of debris, mainly of beds of 

 basaltic tuffs and agglomerates, whose outcrop was in some cases well marked by the 

 lines of kenyte boulders. The regularity of position of these boulders renders it 

 practically certain that they have been weathered out from the basalt, and have not 



