Geology. 281 
gravel; when found at lower depths, it is almost always imbedded in 
clay, usually of a very tenacious kind. 
_ Ballarat Gold-field.—The Ballarat gold-field, which is about fifty- 
five miles north-west of Geelong and Port Philip Bay, lies at the junc- 
tion of the slates with the trappean country, about seven miles from an 
extinct and now forest-grown volcano, known as Mount Boninyongs A 
second similar black volcanic mount rises out of the slate ranges, 
about ten miles due north of Boninyong. Granite crops out in small 
patches between the two Mounts. 
This auriferous tract is united to that of Mount Alexander by a sue- 
cession of similar dark forested ranges, rough, rocky, and sterile, 
strewn over with quartz, and consisting of the same series of micace- 
ous, flinty, and clay-slates. 
olcanic tract.—At the western base of these sombre hills lies a 
large tract of the most fertile and beautiful country—the garden o 
Australia Felix—the rich soil of which is the product of decomposed lava. 
These park-like plains, sprinkled over with groups of trees, are diver- 
si by numerous domelike lava hills, without trees, but of the richest 
verdure. I have counted no less than twenty-four of these remarkable 
bold hills from the summit of one of them. The south and east sides 
action cannot be very remote. Alto ether this voleanic region forms a 
Most interesting subject for geological research and speculation. 
riz Veins.—The sedimentary rocks are traversed by numerous 
Veins of quartz, about 3 feet wide, of unknown length, insome districts 
descending to an unknown depth, in others not more than three or four feet 
deep. These veins or dykes run N. and S., or N.N. E, and. S. W., 
and always make an acute angle with the laminz of the slates. They 
Seem to be the original matrix of all the gold found in the valleys and 
creeks, The quartz is often intersected by many Joints narro 
fissures, filled with a red ferruginous earth, in which particles of gold 
are disseminated. Gold is also found implanted in the quartz itself, 
and attached to the sides of its cavities. ‘These auriferous veins were 
iscovered and wrought before the alluvial gold deposits or “ Diggings ; 
and as they were worked with profit by the 
mand of the untrained diggers, they would doubtless well repay those 
Wa May operate upon them with all the appliances of modern European 
‘Stooxp Seams, Vol. XVIJ, No. 50.— March, 1854. 
