13 



this point. The overlying sheet of basalt is only about 6ft. 

 thick at the extreme point, but becomes massive, probably 

 from repeated flows, towards the west. 



The observations which I was enabled to make regarding 

 the conditions under which the One Tree Point leaf beds 

 were deposited, predisposed me to expect that in the protected 

 bays on either shore of the estuary at a similar level I 

 should find further evidences of the lake system, which even 

 then I had reason to infer must have included the Geilston 

 travertin, which I now regard as a deposit formed in a small 

 bay of this old lako. In this respect my expectations were 

 more than realised, for in carefully examining the coast lines 

 at the first three points I selected for examination, viz., 

 Sandy Bay, Cornelian Bay, Lindisfarne Bay, I discovered 

 sections proving their close relationship, even more remark- 

 able than that at One Tree Point, which first arrested my 

 attention. 



SANDY BAY DEPOSITS. 



At Sandy Bay there are several interesting sections belong- 

 ing to the formation. One of them, beyond Dunkley's 

 Point on the Brown's River road, is composed of a series of 

 clayey and arenaceous beds, irregularly disposed about 30 to 

 40 feet high. It is caj^ped by what appears to be a 

 tufaceous loamy soil. The surface of this loamy bank, like 

 many other points on either side of the Derwent, is covered 

 with a layer of the comminuted remains of existing marine 

 shells, about 1 foot in thickness. The shells appear to have 

 been subjected to fire, for which also there is evidence in the 

 abundance of wood-ashes and charred remains of timber 

 belonging to existing vegetation which enveloped the shells. 



The best and most interesting section at Sandy Bay is 

 to be seen at a small projecting sandy promontory nearly 

 opposite the new Eifle Eange. At this point a series of 

 finely bedded blue and reddish clays more or less arenaceous 

 are tilted at a very high angle against a thick-bedded reddish 

 sandstone of doubtful age. There appears to be a fault at 

 the point where the clays are inclined at a very high angle 

 against the sandstone, and it is evident that a strong lateral 

 pressure has bent them iip into their present form. When we 

 take into consideration the eruptive disturbances subsequent 

 to their deposition, of which, in their vicinity, I have already 

 given evidence, we may reasonably expect consideralde 

 crumplings and fractures of this kind. 



Sketch 3 gives in outline the principal features, and 

 the relations of this section. (See Plate No. S.J 



The fine blue and red clays h are extremely rich in fossil 

 leaf impressions, but as the purer clays are often very soft, 

 and the sandy beds friable, it is difficult to get perfect 



