1857.] SMYTH EXTINCT VOLCANOS OF VICTORIA. 231 



The water in the lake is, I believe, some 25 feet above the level of 

 the sea. A large tract of swampy land, which appears to have been 

 recently upraised, extends from the southern base of the hill to the 

 sea. 



The average slope outwards of the hill is about 6° ; and the inner 

 slope, which forms the margin of the lake, is about 30°. In "the 

 centre of the lake there is an island, irregular in form, on which 

 there are several peaks or extinct craters. 



Mr. H. Cadogan Campbell, C,E., of Warnambool, has kindly 

 favoured me with a description of the strata sunk through in digging 

 a well on the south-east slope of the margin of the lake (see plan). 

 He says : — " They first sank through about 3 feet of soil, and then 

 for about 60 feet passed through layers of ash, alternately black and 

 white, and of irregular thickness, though none above an inch or two. 

 At the depth of 63 feet the workmen came upon the original surface 

 of the ground, covered with the common coarse grass now found 

 growing. It was not scorched, but merely like dry hay." He says 

 again: — " Tower Hill is one of our most extensive volcanos ; but it 

 does not appear that much lava has been ejected from it. What 

 has been thrown out has taken a course to the S.W. 



"An immense quantity of ashes has been thrown out, forming 

 layers of a tufaceous rock, — the greatest quantity to the eastward of 

 the mountain, that being the side towards which the wind generally 



blows This I have also observed at Lake Purmbeet, where 



a similar rock is formed 'from Mount Leura." 



Underneath the ancient humus, the workmen sank 60 feet through 

 a blue and yellow clay. Mr. Selwyn, the Government Geologist, 

 has sent me the following note : — 



" Geological Survey Office, 11th Aug. 1857. 



" Dear Smyth, — I have just returned from a very hasty visit to 

 the Western Ports and Tower Hill ; and with reference to the recent 

 discovery of frogs in sinking a well in that neighbourhood, it may 

 be interesting to you to know that Tower Hill is certainly the most 

 recent volcanic vent I have yet seen in Victoria. 



" It appears, at least during its later eruptions, to have emitted 

 vast quantities of ash and scoriae ; and these are seen near Warnam- 

 bool, resting on beds of shell, sand, and earthy limestone containing 

 numbers of the living littoral species of mollusca. 



" In all other localities where I have examined the large sheets of 

 lava which are so widely distributed over the colony, I have never 

 found them resting on beds of newer date than upper miocene, but 

 have frequently found them, as is the case at Portland, overlaid by 

 beds apparently precisely similar to those which underlie at Warnam- 

 bool the ash and scoriae of the Tower Hill crater. 



" Yours faithfully, 



"Alfred R. C. Selwyn." 



<( B. B. Smyth, Esq., $•<?." 



8. Mount Gambier, in South Australia, rising near the boundary- 



