I V.— GE OLO G Y, 



Art. XL VI I. — -The Kingston Moraine. 



By Dr. P. Marshall. 



[Read before the Otago Institute, 8th July, 1902.~\ 



During a short stay at Kingston in March, 1902, an exami- 

 nation was made of the moraine at the south-east end of 

 Lake Wakatipu. The examination was made with the object 

 of finding, if possible, the limits of the area from which the 

 ice forming the large glacier that formerly filled the lake- 

 basin was derived. 



The materials of the moraine were found to consist almost 

 entirely of mica-schist, phyllite and aphanite breccia, which 

 constitute the mass of the mountain-ranges by which the 

 lake-basin is bounded. 



On the shore of the lake the materials of the moraine have 

 been subjected to a sorting action by the breaking waves, and 

 those stones consisting of the more resistant materials have 

 become more concentrated. On this beach, about a mile 

 from the hotel, were found twelve stones which, in consequence 

 of their absence from the rock-masses near the lake, offered 

 suitable material for study. These rocks may be classified as 

 follows : — 



(B 102.) Granite. — Light-grey rock of even granular ap- 

 pearance. Except for decomposed feldspar, the separate 

 minerals cannot be distinguished. Section : Quartz in clear 

 grains completely allotriomorphic. Feldspar completely de- 

 composed, revealing nothing of its original nature. Decom- 

 position products chiefly quartz and muscovite flakes with 

 epidote. A few small grains of amphibole of a fibrous 

 structure with strong pleochroism. Small grains of biotite 

 with strong absorption occur here and there in groups with- 

 out any relation to the neighbouring minerals. The actino- 

 litic amphibole and biotite are evidently secondary in their 

 origin. 



(B 101.) Granite. — Similar to B 102 in general appear- 

 ance. Section : Similar to B 102, but the feldspar is much 

 fresher, and is found to consist partly of orthoclase, partly of 

 oligoclase, and perhaps albite. Plagioclase is more plentiful 

 than orthoclase, and is twinned freely on the albite law and 



