358 PROCEEDINGS OF SECTION C. 



In the old Don Company's ground the deposit is of a 

 different character. Beneath the surface soil we find tin 

 drift varying in thickness ; below that occurs a black or grey 

 clay (in places fireclay), through which a large quantity of 

 leaf impressions and lignite is distributed, just like real 

 lead material, and below that occurs another layer of heavy 

 wash. An attempt was made to prospect this formation, and 

 a shaft was sunk to a depth of about 100 feet before the 

 bottom was reached. The work was very heavy — boulders 

 tons in weight having to be broken and sent up the shaft — 

 and the washdirt found amongst the boulders, although fairly 

 good in places, was not sufficient to pay for the work. As 

 the company was, besides, not a strong one, the undertaking 

 had to be abandoned before any definite information Avas 

 gained. All we know, so far, is that the bottom rises rapidly 

 northward and is very uneven. This deposit may be the 

 commencement of a deep lead. 



Although the prospects appeared not very encouraging, 

 still, to set the question about the existence of a deep lead at 

 rest, a prospecting company was formed, and, with the help 

 of the Government diamond drill, a series of bores were put 

 down about three-quarters of a mile south-west of the Don 

 Company's ground, with the result that deep ground was 

 discovered, but without any trace of tin ore, or even of the tin 

 porphyry. There the matter rests at present, but it remains 

 still a moot question whether the lead, if one exists ar, all, 

 does not take a different course to that supposed by those 

 interested in the company just alluded to, and as indicated 

 by the borer. 



In conclusion, I must state that in the foregoing paper I 

 have endeavoured to bring under the notice of the Members 

 all the leading features of the mine and its surroundings. I 

 am conscious of the imperfection with which I have carried 

 out my task, and hope that some more capable geologist 

 than myself will at no distant date make the geology and 

 mineralogy of the Mount his special study. 



A geological map of Mount Bischoff, compiled about 

 twelve months ago, accompanies this paper, and may help 

 to explain the foregoing. 



8.— ON THE AGE OF MAMMALIFEROUS DEPOSITS 

 TN AUSTRALIA. 



Bij Professor TATE, F.G.S. 



