Marshall. — Geological Notes. 565 



however, the green mineral that was evident in hand-specimens 

 was not represented in any of the sections, and Professor Ulrich 

 provisionally referred it to enstatite, which was present in quan- 

 tity. Ulrich referred the rock to the group of saxonites of 

 Wadsworth — that is, the hartzbergites of Rosenbusch and other 

 authors. The demonstration of the fact that the green mine- 

 ral is diopside, which is easily done in the sections now before 

 me, justifies the classification of this rock with the Iherzolites. 

 A section of this rock was sent some months ago to Professor 

 Rosenbusch of Heidelberg. The section, however, was in some 

 respects exceptional, for but little olivine was present ; and Pro- 

 fessor Rosenbusch stated that the rock was a websterite, a 

 connecting-link between the hartzbergites and the pyroxenites. 

 A partial cataclastic structure was also remarked upon. See- 

 ing that in the greater part of the rock olivine is very abundant, 

 I feel justified in classing the rock with the Iherzolites in spite 

 of the statement of the eminent authority. I would wish, how- 

 ever, to put on record my deep sense of gratitude to Professor 

 Rosenbusch for the kindness and assistance that he has so 

 readily extended to me. 



Dunite. — A large mass of the rock is of a dark-slate colour, 

 weathered on the surface to a dull-brown. In hand-specimens 

 it appeared perfectly dense ; sections, however, showed at once 

 that the rock is really a dunite in process of serpentinisation. 

 A little chromite and pyroxene are present, but the greater 

 portion is a mass of olivine-grains traversed in all directions 

 by small veins of serpentine, forming a very complete mesh 

 structure. 



The arrangement of these rocks is shown in the plan on the 

 following page. 



The weather effectually prevented an exact demarcation of 

 the boundaries of the different rock-types, and the approximate 

 boundary of the lherzolite was made out observing the colour 

 of the rocks where they emerged above the snow in the distance. 

 It will be noticed that the igneous rocks are bounded by 

 schists on the east and by the Te Anau breccia on the west. 

 The latter, however, may quite possibly be the effusive type ami 

 associated fragmentary rocks of the diorite magma adjacent to it. 

 From the boundary of the diorite there is a regular increase of 

 basicity until the lherzolite is reached. At the south end of the 

 area the lherzolite is certainly in direct contact with the schist on 

 the east side. So far as could be seen the division-lines between 

 the different rocks correspond in direction and inclination with 

 those of the schist. If this should finally prove to be the case, 

 further work will be necessary to decide whether the igneous 

 mass was a laccolite that has since been subject to the same 



