Gl 
consist of fine-grained gneiss, the granitic outcrops being in 
the heart of the range. The main intrusion thus extends east 
of the pass towards Mount Woodroffe, thence taking a more 
northerly turn in direction of Mount Carnarvon ; it has its 
greatest development east of Harries' Spring, while on the 
eastern borders of the range gneisses predominate. In this 
respect the Musgrave resemble the Mann Ranges 
A subsidiary arm of the main injection of the igneous 
rock produces a prominence in the neighbourhood of Mit- 
chell's Knob, the major and minor veins of the same enclosing 
clastic (?) gneisses. (See fig. 1.) 
The ranges on the northern flanks, north of Mount Fer- 
dinand, j^resent a picturesque appearance, produced by gro- 
tesquely shajDed, isolated, bare, granitic masses ( S^skunddre 
Kwppen). 
The granite, particularly that of the porphyritic variety, 
is characterised in the field by its strong tendency towards 
concentric weathering, large shells of rock exfoliating con- 
centrically to the present contour of the rock surface. This 
feature is deserving of particular notice. 
In the valley of the Ferdinand, west of the mount bear- 
ing a similar name, the character of the granite changes to a 
more even-grained, white variety, with irregular aggregates 
of hornblende and biotite distributed through its mass. 
Where this granite has been cut by diorite the contact is 
marked by a development of large idiomorphic crystals of 
hornblende. In the same locality minor veins of epidote 
granite, with a red orthoclase felspar, and graphic granite 
traverse the main granitic mass in a westerly course. 
East of Lungley's Gully an intrusion of red aplite is deli- 
cately veined with crystalline epidote, and the planes of slick- 
ensiding, that cut the rock, are lined with a ''harnisli'' of 
secondary mica and rhombohedral calcite. The vr>c\ is con- 
spicuously jointed in two planes, the first of which strikes 
W., 20° N., and dips northerly 73°, the second striking 
N., 45° E., and dipping 23° S.E. ; a third plane is less regu- 
lar. Rocks belonging to the peridotite family were found in 
the form of pebbles among the wash of a small watercoarse 
south of Mount Morris, but the rock was not observed in situ. 
Diorite dykes are very plentiful. The diorite rock is rormai, 
quartzless, and moderately fine-grained. It is usuall/ Drupa- 
ceous. Dolerite dykes are less numerous. They consist of a 
finely crystalline ground mass with porphyritic crystals of 
felspar and pseudomorphous ( 1) epidote. Dykes of a 
peculiar volcanic rock are rare. Fluidal structure is typical 
when viewed under the microscope, it being marked by ores 
