60 
and the altitude is considerable. Mount Woodroffe, the 
highest peak, is estimated to be over 5,000 feet above sea 
level, and more than 3,000 feet above the level of the adjoin- 
ing desert. Hence this chain of mountains is by far the most 
massive of the series seen during the expedition. 
Igneous intrusions on a grand scale have produced the 
upheaval and form the inner mass of the several folds into 
which the intruded metamorphic beds have been thrown. 
Mr. W. C. Gosse, in 1874, pointei out that the Mus- 
grave Ranges "are composed chiefly oi granite,"^ and later 
Mr. H. Y. L. Brown t (1889) that they -are composed of 
eruptive granite and metamorphic granite rocks of various 
kinds, chiefly hornblendic, and seldom containing mica," 
comprising "ordinary granite, porphyritic granite, horn- 
blendic granite, graphic granite, granulite, pegmatite, 
syenite, quartz syenite, and epidosite, gneiss, both horn- 
blendic and micaceous, and siliceous and felspathic crystal- 
line rocks of various kinds," and that they are intruded by 
diorite and dolerite. Mr. .J. Carruthers stated : — 
I ''The Musgrave Ranges are composed principally 
of red granite rocks, and covered with spinifex 
and few scattered pines ; the flats between the hills, 
which are principally formed by large creeks coming out of 
the ranges, are beautifully grassed, . . . the soils being 
a rich, red, sandy alluvial, and tirm red loam." 
Igneous Rocks, — The intrusives vary in character from 
highly acidic to basic, the differences, however, between the 
members of one and the same family being slight. The acid 
rocks are principally granitic, the greater bulk consisting of 
a rather coarse-grained porphyritic variety, with large cor- 
roded crystals of a bluish felspar (orthoclase). Ernest Giles 
was the first to mention;^ this type of granite, and assigned to 
it the expressive term of "granite-conglomerate," making 
thereby particular reference to Mount Carnarvon, which is 
the eastern limit of the Musgrave Ranges. Mr. W. C. Gos^e, 
moreover, in describing Mount Morris, wrote || "that this 
portion of the range is composed of very coarse granite. At 
the entrance to Jacky's Pass, on the south, this class of 
granite flanks the chain, but further east the southern slopes 
* Parliamentai*y Paper, No. 48, House Assembly, page 18. 
t Report on Jouniey from Warrina to Musgi-ave Ranges. By 
authority: 1889. 
t Report to Surveyor General (Adelaide Observer, January 
16, 1892). 
§Ge<)gr. Travels in Centr. Austr., 1872-1873, Part ii.. page 84. 
II Parliamentary Paper, No. 48, House Assembly, 1874, page 
16. 
