7 
Along the new track from Hall’s Gap to the Gates of the West there are 
several outcrops of porphyry, and further south along the range past Wonder¬ 
land there is a larger mass of similar rock, with quartzite on its eastern 
•contact. 
Just below the retaining wall of the Wartook Reservoir, a dense, dark- 
blue basic rock occurs in the Grampian sandstones, but the surface here is 
marshy, and the relation of the rocks was not observed. At the Broken Falls, 
McKenzie Creek, a fine contact, in plan, between Grampian sandstones and 
porphyry was noted ; and, at the foot of the Big Fall, a vertical contact is 
very clearly exposed; in both places the porphyry certainly appears to be 
intrusive. Hand specimens of some of the actual contacts are exhibited in 
the Geological Survey Museum. 
Extent of the Grampian Sandstones. 
The main mass of the Grampian sandstones outcrops between Mount Zero 
on the north, Dunkeld on the south, Moyston on the east, and Cavendish on 
the west, with outlying portions on the west at the Dundas and Black Ranges, 
and at Mount Arapiles. To the south a small outcrop occurs near Wiekliffe 
which probably marks the southern limit of the formation in that locality as 
it consists of a boulder-conglomerate in which stones up to a foot in diameter 
were noted. * 1 It was probably deposited on a shore line of Ordovician rocks, 
portions of which are included in the conglomerate. This is the southern 
limit in this locality, but, southwards from Dunkeld, the sandstones may 
extend under the Tertiary basalts towards the coast. 
West of the Dundas Range, most of the sandstones —if they ever existed 
—have been removed by denudation, for older rocks outcrop in many places 
In this direction. 
R. A. F. Murray, 2 formerly Government Geologist, has given some notes 
on the Grampian sandstones and their northern extension. 
“ That these Grampian sandstones extend under the Tertiary deposits 
of portion of the North-Western District has been proved by a bore at 
Netherby, near Nhill, to a depth of 2,200 feet. The cores obtained below 
the Tertiary deposits consist of nearly horizontally bedded, laminar shales 
sandstones, conglomerates, and breccias. 
“ The conglomerates contained boulders of gneissose schist and granite 
and yielded in some cases a trace of gold on assay. The bore left oil m 
porphyry, but whether an intrusive mass underlying the sedimentary strata 
or a layer interbedded with them is not 'known. 
“ It is evident, however, that the rocks of the Grampian sandstone series 
extend north-westerly beyond their northernmost exposures near Horsham 
and Mount Arapiles, a long distance towards the Murray.” 
Murray further states that from the results of boring operations extending 
from near Donald towards Lake Tyrrell, the Ordovician rocks of Wedderburn 
extend north-westerly towards that lake and would limit the eastward 
extension of the Grampian formation so far north, but, further south, he does 
not consider that the sandstones extend further east than a line from Horsham 
do Lake Boga. The utmost possible western limit he considers to be the 
granite of the Coorong, South Australia. 
Apparently, the now visible Grampian sandstones are but a remnant — 
which has escaped denudation—of a once widespread formation. 
1 W. H. Ferguson, Prog. B,ept. Geol. Surv., Viet., No. IX., 1S89, p. 176. 
1 Annual Kept. Sec. for Mines, 1889, p. 18. 
