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 

 ordinary earthquake did not exc^xl 10, 12, or 14 feet per second, being about, 

 that which a body would obtain by falliug off a table. The extreme limit of 

 earthquake-wave velocity appeared never to reach more than 80 feet per 

 second. The only example of this high velocity was mentioned by Humboldt 

 as occurring in the liio Grande, where, 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 14 feet velocity at Naples, and 80 feet in this 

 latter case, corresponded with the respective heights of the volcanic mountains. 



THE EXTINCT VOLCANOS OF WESTERN VICTORIA. 



By Mr, James Boxwick, 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. The 

 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 Victoria, by the 

 Glenelg. The great basaltic plain of the 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 in length, exist in the basaltic floor of the 

 plains. On the south-west side of the great salt-lake Corangamite, there are 

 basaltic " rises." Below are huge barriers from 10 to 60 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, and at Pompeii. It is oc- 

 casionally sufficiently solidified to be lit for building-stone. Carvings, however, 

 are very commonly made of it in the district. The ash and cinder-conglo- 

 merate exist but in one place — the Island of Lawrence, in the Portland Bay. 

 Cliffs 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- 

 canos are in the form of lakes and mountains. The lakes are depressions 

 usually on slight eminences. Terang, Elingamite, Purrumbete, AVangoon, and 

 Lower Hill are fresh, while Keilambete and Bulleenmerri are salt. The 

 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 

 2G0 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 asli 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 on? > °n the 

 eastern side, it is 150 feet. The volcanic hills "vary from a few yard s to aboet 

 2,000 feet above the sea-level. The depth of the dry craters runs fiom50 fer. 

 to 300 feet. Gambler and Schanck are within the South Australian bordes 

 The former has three fine lakes, the latter is a dry basin, known as the Devil' 



