74 Geological Society : — 



2. " On the Extinct Volcanos of Victoria, Australia." By 

 R. Brough Smyth, Esq., C.E., F.G.S. 



The district in Southern Australia in which lavas, hasalts, and 

 other evidences of recent igneous action are found extends from the 

 River Plenty (a tributary of the Yarra), on the east, to Mount Gam- 

 bier on the west. Its most northern point is Macneil's Creek (a 

 tributary of the Loddon), in 37° S. Lat., and its most southern point 

 is Belfast, in 38° 21' S. Lat. Its extreme length is 250 miles, and 

 its extreme breadth about 90 miles. 



The following were enumerated and described as the most 

 distinctly marked crateriform volcanic hills : — 



1. A hill near the source of the Merri Creek, on the Dividing 

 Range, about 25 miles north of Melbourne, and already described 

 by Mr. Selwyn, the Government Geologist. 2. I\Iount Atkin, about 

 1500 feet above the sea-level. 3. Mount Boniuyong, adjacent to 

 the Baliarat Gold-fields. 4. Larnebaramul or Mount Franklyn. 

 5. Mount Rouse. 6. Several crateriform hills around Lake Korau- 

 gamite, and the often conical hills known as the Stony Rises. 7. 

 Tower Hill, between the towns of Warnambool and Belfast, and 

 close to the coast. In the last-mentioned instance the scorise have 

 been found by well-sinkers to overlie, at the depth of Go feet, the 

 original surface of the ground, covered with coarse grass, such as 

 that now found growing, and amongst this dry, but not scorched, 

 grass the workmen are said to have found some living frogs. 



Over nearly the whole extent of Victoria there are masses of 

 intrusive basalt, in some places columnar, breaking through both 

 the granite and the palseozoic strata, and occasionally through the 

 overlying Tertiary (Miocene) beds also. Extensive denudation has 

 destroyed the probably overlying j)ortions of these old basaltic 

 outbursts, both before and after the tertiary period. A newer series 

 of eruptive trap-rocks, sometimes as dense and hard as the older 

 basalts, but more frequently vesicular and amygdaloidal, pierce the 

 old tertiary and also the post-tertiary beds, or the later quartzose and 

 auriferous drifts. These newer basalts and lavas were probably 

 erupted at a period when considerable areas, both north and south 

 of the main coast-range, were submerged ; and the lavas cooled 

 rapidly and not under very great pressure. These eruptions do not 

 appear to have disturbed the Tertiary beds, which are usually found 

 nearly horizontal. After these newer basaltic lavas were erupted 

 and denuded, and after the deposition of the overlying pleistocene 

 drift, some of the volcanos were still acting, though not so energetic 

 as previously, emitting porous lavas and pumice ; and at a still later 

 period volcanic ash and scoriae, such as that wbich rests on the 

 ancient humus at Tower Hill, and that of Mount Leura and the 

 Koraugamite district, were thrown out when the igneous force was 

 almost exhausted. Mr. R. B. Smyth pointed out the interest attached 

 to the extinct volcanos of Victoria as connected with the great vol- 

 canic chain extending from the Aleutian Islands to New Zealand ; 

 and concluded with some observations on the recent occurrence of 

 earthquake-movements in Southern Australia, and on the evident 



