252 
a quantity of dark mica in flakes up to \ inch in diameter. There are 
numerous fragments of slate, which have apparently been in the pipe and 
have been rendered somewhat flinty in character. In the orchard there was 
found a small piece of very cellular siliceous stone which may be a form 
of sinter, and hydrothermal action is also suggested by a fragment of 
chalcedonic quartz, which is arranged with layers of either alumina or 
hydrated silica. The most interesting piece of stone found is a small 
fragment of tuff which contains crystals of partly decomposed hornblende, 
crystals of dark mica, and a fragment of slate. 
Mr. Young informs me that a well was sunk to a depth of 23 feet 
through the strata here mentioned— 
11 feet black soil 
3 feet black clay 
2 feet black volcanic clay 
7 feet yellow clay with mica (decomposed tuff) 
23 feet. 
This hole was sunk in the gully only a few feet from the Ordovician 
rock. Concentrates from a dish of surface soil contain a few small pieces 
of what appear to be garnet. The soil grows fruit trees well, and fine 
crops of potatoes, onions, and maize. 
This pipe resembles in many respects the one at Point Kruger, near 
Cape Paterson; it is probably the lower portion of one of the volcanoes of 
Older Volcanic age, and from it may have ccme some of the Older Vol¬ 
canic lava which is shown on the Maude quarter-sheet. 
[ 6 . 12 ^ 0 ?.] 
SAND SUITABLE FOR GLASS-MAKING, DOG TRAP GULLY, 
NEAR BACCHUS MARSH. 
By E. J. Dunn , F.G.S., late Director , Geological Survey. 
At Dog Trap Gully, near Bacchus Marsh, 100 feet of alternating beds 
of fine white clay, clay with sand, coarse sand, and extremely fine sand, are 
exposed in a cutting. The beds range from a few feet to many feet in 
thickness. 
The bed of verv fine sand appeared suitable for glass-making, and 
some was sent to Messrs. Knott Bros, to test. They made glass from it, 
and expressed a favorable opinion on it. 
As taken from the seam this sand analyzed in the Departmental 
Laboratory as under: — 
Silica ... ... ... ... 96.46 
Alumina ... ... ... ... 2.27 
Iron Oxide ... ... ... 0.15 
98.88 
