67 
The plane of contact with the primary gneisses is mostly 
imperceptible. A contact zone is not infrequently found 
gradually merging into granite on the one side, and granitic 
gneiss on the other. In other cases the contact has been so 
fractured and dislocated for a considerable distance that the 
junction cannot be traced. 
Large "floating" masses of bedrock were noted at several 
localities, as, for instance, north-west of Mount Whinham 
and south of Mount Edwin. 
The granite in general occurs as bare, rounded, dome- 
shaped masses,"^ several chains' length of rock often appearing 
without the least fracture in the mass, though subsequent 
weathering produces large exfoliating shells, which detach 
themselves from the body of rock (concentric weathering). 
This feature is more usually presented by the porphyritic 
varieties, while a more typical granitic aspect is brought 
about by the natural systematic jointing of the fine-grained, 
uniformly crystalline rock. Frequently the mass shows nei- 
ther of these physical features, but is grossly shattered 
throughout by the intense stress produced during the process 
of solidification of the crystallizing rock magma. Such in- 
stances were found south' of Mount Cockburn, and on a 
splendid scale south-east of Hector's Pass, where the planes 
of fracture have assumed regular, contorted, and curved out- 
lines, as though produced during the last stages of solidifica- 
tion of the magma, the more rapidly contracting envelope of 
the rock having caused the enclosed mass to part alon?" cer- 
tain curves of stress by virtue of the extreme pressure" from 
without. 
Diorite dykes are very numerous, forming a fairly regu- 
lar system, usually, though not invariably, trending east and 
west. The best noted example of excessive intrusion by this 
rock was observed in the hills east of Mount Whinham, on 
the eastern extremity of the ranges. At this locality no' less 
than fourteen diorite dykes can be counted traversing the 
gneissic hills m a distance of less than a quarter-mile^ and 
can be clearly seen continued through a similar gneissic 
exposure a mile or two further west. 
Metamorphic Eocks.— As stated above, crystalline schists 
and gneisses appear more extensively developed at the eastern 
end of the chain. Ne ar the north-western limit of the main 
XT. T-^^^^"^ ^^P- ^^^-^ continues his statement:—". most of 
the higher points of all these heights are composed' of' frowning 
mas^ses of black-lookmg or intensely i-ed ironstone or granite^oat? 
ed with iron. Trtocha grows as far up the sides as it is po^^ble 
to obtain any soil but even this plant cannot exist upon solid rock 
therefore all the summits of these hills are bare." 
