PROCEEDINGS OF GEOLOGICAL SOCIETIES. 
543 
three years ago, on experimenting at Naples, that he satisfied himself that the 
wave-particle velocity was extremely low. The wave-partical velocity in any 
ordinaiy earthquake did not excec^:! 10, 12, or li feet per second, being about 
that which a body would obtain by falling oif a table. The extreme limit of 
eartliciuake-wave velocity appeared never to reach more than 80 feet per 
secoua. The only example of this high velocity was mentioned by Humboldt 
as occurring in the Rio Grande, wliere, during an earthquake, the bodies of 
men were thrown upon a bank nearly 100 feet high. The shock was in this 
case vertical, and the force was equal to a velocity of about SO feet per second. 
It was a curious fact that the 11? feet velocity at Naples, and SO feet in this 
latter c^^,e, corresponded with the respective heights of the volcanic mountains. 
THE EXTINCT VOLCANOS OF WESTERN VICTORIA. 
By Mr. James Bokwick, F.G.S. 
Mr. James Borwick denominated the south-western part of Victoria and 
the adjacent portion of South Australia the "burnt fields" of Australia. Tlie 
country referred to lies chiefly between the slate and granite dividing the 
diggings and tertiary limestone of the sea-coast, and has an area of nearly 
half the size of England, extending from the Bay of Port Phillip, near Mel- 
bourne and Geelong, to beyond the western border of A'ictoria, by tlie 
Glenelg. The great basaltic plain of tlie west has few interruptions from the 
bay to the border, and from the shore to the central range. The basalt is of 
all varieties, and furnishes in its decomposition the finest soil to the agricul- 
turist. Many rounded lava hills are found on the plateau of the dividing 
range ; and caverns, nearly 500 feet m length, exist in the basaltic floor of the 
plains. On the south-M'cst side of the ^reat salt-lake Corangamite, there are 
Dasaltic " rises." Below are huge barriers from 10 to GO feet in height, 15 
miles long by 12 broad. The ash or tufa has the same appearances as that 
the author observed at Lake Albano, near Home, ajid at Pompeii. It is oc- 
casionally sufficiently solidified to be fit for building-stone. Carvings, however, 
are very commonly made of it in the district. Tlie ash and cinder-conglo- 
merate exist but in one place — tlie Island of Lawrence, in the Portland Bay. 
Clitfs of this singular compound rise there to 150 feet. The author's impres- 
sion is, that the source was a submarine volcano to the south-west — the course 
of the prevailing wind and current ; and that the ashes and volcanic dust were 
received in some sheltered bay, since raised with the coast. The extinct yol- 
eanos are in the form of lakes and mountains. The lakes are^ depressions 
usually on slight eminences. Terang, Elingamite, Purrumbete, "Wangoon, and 
Lower Hill are fresh, while Keilambele and Bulleeninerri are salt. Tiic 
shallow saline lakes of the plains were not former craters. The depths of these 
lakes are from 50 to 300 feet. The Devil's Inkstand of Mount Gambler is 
260 feet. The banks vary from a few feet to 300 feet in height above the 
water. The circumference varies from a hundred yards to seven miles. The 
thickness of the ash increases with the distance from the crater, but is always 
thickest on the eastern side. At Lower Hill, at a quarter of a mile from the 
bank, on the northern quarter, it is 80 feet deep, while at a mile off> on the 
eastern side, it is 150 feet. The volcanic hills vary from a few jsxv(\.^ aboet 
2,000 feet above the sea-level. The depth of the dry craters runs fiomSO fer. 
to 300 feet. Gambier and Schanck are within the South Australian hordes 
The former has tiirec fine lakes, the latter is a dry^basin, known as the Devil' 
