688 BOTANY OF THE INTERIOR OF NEW SOUTH WALES, 



and sea on the east coast during recent geological times; and that 

 the coast line formerly extended as far to the east as the edge of 

 the continental shelf (the present 100 fathom line).* In this case 

 the land around Burrill was formerly higher, and the salt water 

 would have been kept back at least some miles to the eastward. 

 Under these conditions the present bed of Burrill would be 

 occupied as a small fresh water river probabl}'' lined on both sides 

 with River Oaks. As the alteration of level progressed the salt 

 water would be likely to encroach and destroy all the fresh water 

 Oaks except the few under discussion; and had the alteration 

 continued longer even all trace of these might have disappeared. 

 At the same time, too, the altered conditions would be likely to 

 induce the westerly extension of the salt water Swamp Oak to 

 its present limits. 



There appears to be geological evidence to support this view, 

 and I have collected fossils near the mouth of Burrill, at present 

 water level, and similar ones again on the top of the Pigeon 

 House, 2360 feet higher, and about a dozen miles to the west- 

 ward, which prove the formation in both cases to be the same, 

 viz., Permo-Carboniferous. 



Altogether the case presents some interesting features, and is 

 one in which the study of the geological changes might be 

 assisted by a knowledge of botany (Plate xxxiii.). 



C. Cunniyigliayniana is the common Oak tree found on the 

 upper parts of most of the New South Wales rivers, and although 

 it follows up the large creeks in their ramifications among the 

 mountains it never leaves the vicinity of the stream, and is there- 

 fore never found on the hillsides among the Forest Oaks. 



* See Prof. David's " Anniversary Address " to the Eoyal Society of New 

 South Wales, May, 1896. Journ. and Proc. R. Soc. N.S.W., Vol. xxx,, 

 pp. 43, 48, 69. 



Also a paper " On the Occurrence of a Submerged Forest with Remains 

 of the Dugong at Shea's Creek, near Sydney." By R. Etheridge, Junr., 

 Prof. David, and J. W. Grimshaw, Op. cit. pp. 160, 176, 178. 



