234 T. W. E. DAVID AND G. H. HALLIGAN. 
At 62 feet numbers of roots of trees and charcoal were 
met with embedded in a carbonaceous sandy clay, and at a 
total of 65 feet a perfect cone of Casuarina was brought 
up by the sand pump. At 56 feet the formation became a 
dark peaty sand, probably of terrestrial or lacustrine origin; 
at 71 feet this gave place to dark peaty sand passing down- 
wards into sharp clean sand, with occasionally white quartz 
pebbles, one-third to one-quarter inch diameter associated 
with fragments of plants. The last 4 feet of the boring 
was in coarse gravelly sand with pebbles of Hawkesbury 
sandstone up to 1 inch in diameter, with occasional frag- 
ments of lignite. 
As the bore progressed we were careful from time to 
time to test the water which came up in the bore for salt- 
hess with a view of deciding to what depth the layer of 
freshwater bearing sand extended. We were somewhat 
surprised to find that the water in the sands was fresh to 
a depth of about 14 feet below high water. This is 
obviously due to the fact that there is a considerable mass 
of water bearing sand forminga broad and high bank on the 
seaward side of the bore; this bank rises toa height of 
about 35 feet above sea level, and it is no doubt the siow 
movement under hydraulic pressure of the water from this 
sand bank seawards that forces back the salt water. We 
were informed by residents in the neighbourhood that after 
a prolonged drought the top of the salt water zone comes 
within about 4 feet of the level of high water. 
With reference to the various organisms obtained from 
this bore, Mr. C. Hedley, F.L.S., has examined the Mollusca 
and other Invertebrates, and reports: — 
(1) The species are all recent. 
(2) And are all components of the mud fauna. 
(3) They belong to between tide marks and to the zone 
immediately below low water. 
