73 
Mount Gosse, W.A. 
Mount Gosse is situated in Western Australia, about 
two miles from the boundary of that State and South Aus- 
tralia, and ten miles north of the projected border line 
between the Northern Territory and South Australia. It is 
composed of an intrusion of granite within schistose to 
granitic gneiss, the foliation of which strikes west, slightly 
north. The rock shows cubical jointing, and the gneissic 
rocks are overlaid by a compact blue quartzite* possessing a 
perfect conchoidal fracture, the whole formation being tra- 
versed by the never-failing diorite. 
A prominent hill, situated seven miles east of north of 
Mount Gosse, and almost on the border line, stands 2,250 
feet above sea level, and 325 feet above the desert, which 
bears Xdntliorrlujea and Trindia. It has been determined by 
an intrusion of granite, with porphyritic blue felspars, the 
trend of the intrusion being slightly north of west. 
The injection lies within a linearly foliated gneiss, show- 
ing closely set veinlets of quartz. In portions the gneiss is 
schistose, or slightly fissile, and passes to a fine-grained, 
felsitoid quartzite. Minor veins of graphic granite, with a 
white (decomposed) felspar matrix, and epidote, are also 
met with. 
ToMKiNSON Ranges. 
General Remarks. — These ranges occupy the north-west- 
ern corner of the State of South Australia proper, and ex- 
tend westward to beyond the border into Western Australia 
(Mount Hinckley). They were named by Gosse in 1873. 
Generally speaking, their dominant features are similar to 
those of the Musgrave and Mann Ranges, namely, igneous 
intrusions within crystalline gneisses. In the case of the 
Tomkinson Ranges, however, the intrusive rock consists 
largely of gabbro, accompanied by diorite dykes. Moreover, 
the ranges are not as persistent and compact as those already 
described. 
The higher intrusive bosses bear scanty vegetation, as 
porcupine grass, t mallee, and pine, while the lower spurs of 
gneiss are covered with mulga and kangaroo grass. The 
intervening gullies and flats were thickly clothed with grass 
and herbs. 
* "The formation at Mount Gosse is a quartzite, with fre- 
quent diorite veins and dykes, . . ." W. R. Murray, Ex- 
tracts from Journals of Explorations, bv R. T. Maurice (bv Autho- 
rity : 1904), page 17. 
t See also E. Giles, Geoer. Travels in Centr. Austr., 1872- 
1874, II., page 103; and J. Carriithers : — "These hills are covered 
with spinifex, . . ." — Report to Sur\'eyor-General (Adelaide 
Ohserver, January 16, 1892), 
