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circular, with a small lake at the bottom. The eastern 

 crater^ 19 ) is nearly of the same size as the western, and com- 

 prises a large lake of great depth, which cannot be visited, 

 as there are precipitous rocks all round." This writer gives 

 the approximate widths of the various craters, but does not 

 mention the possibility of enlargement by subsidence. The 

 Rev. J. E. T. Woods (see Ref. No. 2) believed that there 

 were five craters: — (1) The west end of the Valley Lake (now 

 Browne or Crater Lake) ; (2) The east end of the Valley Lake 

 (now Valley Lake) ; (3) the Centre Lake (now Leg of Mutton 

 Lake); (4) Blue Lake; (5) the Punch-bowl (regarding this 

 crater he was in some doubt, and did not have the evidence 

 now available in the bare walls of this depression). Woods 

 gives full value to the matter of enlargement of the craters 

 by collapse. His notes on the general history of the Mount 

 are evidence of the careful and accurate observations made, 

 and show a keen appreciation of the problems involved. Not- 

 withstanding the great advance made in the knowledge of 

 vulcanism since he wrote, no subsequent writings on Mount 

 Gambier can properly summarize or replace the material of 

 Chapter VIII. of his book (Ref. No. 2). 



H. Y. L. Brown (see Ref. No. 3) confines his remarks 

 mainly to the depth, temperature, and origin of the waters 

 of the lakes. In the section accompanying his report he 

 marks only one ''undoubted crater," that near the point 

 where the Tower stands, and he writes: — "From the contour 

 of the Blue, and Valley Lakes . . . together with the 

 appearances in their neighbourhoods, I think that they are 

 not craters, but merely depressions caused by subsidence of 

 the crust, consequent on the removal from below of such vast 

 quantities of material as it is evident that has been erupted." 



Professor Howchin (see Ref. No. 4) supports the views 

 of the previous writer on this point, adding: — •"The qua- 

 quaversal dip points to one centre of ejectment, while the 

 depressed areas of the Blue Lake, the Leg of Mutton Lake, 

 and the Valley Lake are undoubtedly sunken areas, the sub- 

 sidence taking place late in the period of activity, or even after 

 the volcano ceased to eject material." 



(b) Contour Map. — The writer has made repeated efforts 

 to confirm this conclusion of Professor Howchin, but his 

 accumulated observations of both dip and contour strongly 

 support the conclusion of Woods that there was a very im- 

 portant crater situated somewhere near the centre of the 

 collapsed area that now contains the Blue Lake. The evidence 

 for an undoubted crater near the foot of Tower Point (Mount 

 Gambier proper) is equally clear. 



(19) Blue Lake. 

 . g2 



