230 T. W. E. DAVID AND G. H. HALLIGAN. 
with these peat beds. The peat beds and trees were 
covered by estuarine beds containing an abundance of 
marine shells. Reference was made in the same paper to 
the discovery of the skeleton of a large Dugong a little 
above the horizon of the submerged forest, the bones show- 
ing evidence of having been hacked by stone tomahawks. 
The evidence thus supplied was conclusive as to recent 
submergence in the neighbourhood of Botany Bay of at 
least 15 feet. The evidence about to be given shows at 
Narrabeen a probable recent submergence of over 50 feet. 
II. Evidences of recent submergence deduced from 
general physical features.—It has long ago been pointed 
out by the late Rev. W. B. Clarke, the late Government. 
Geologist, Mr. C. 8. Wilkinson, Mr. E. C. Andrews,’ and 
one of the authors, that the numerous deep inlets along 
the coast, such as those of Lake Macquarie, Tuggerah 
Lakes, Broken Bay, Port Jackson, Botany Bay, Port 
Hacking, etc., were distinct evidence of recent coastal 
submergence. As the result of the submergence the old 
land valleys, such as those of Cook’s River, Parramatta 
River, Hawkesbury River, etc. were betrunked through 
the lower ends of the valleys being drowned, as the con- 
sequence of the sea water creeping further and further 
inland as the subsidences progressed. 
The physical features along our coast, particularly those 
of the Narrabeen Lagoon and its neighbourhood, show that 
this submergence, though recent from a geological point of 
view, must date back many hundreds of years, probably 
many thousands of years into the past. This is obvious 
from the large amount of reclamation work accomplished 
’ Proc. Linn, Soc. N. S. Wales. 
*'T. W. E. David, Summary of our present knowledge of the Structure 
and Origin of the Blue Mountains of New South Wales. This Journal, 
xxx, 1896, pp. 33-69, pl. i—iv. 
= 
