90 ANNIVERSARY ADDRESS. 
both ends of the lake, where the ground is flat, as well as along the 
sides, point to a duration of present conditions which is very hard 
to reaiize. At the present time there is a gravel ridge a short 
distance from the water atthe south end. It is 1} mile long, has 
been tested for ballast for the railway, and found to beat least 15 
feet thick where deepest, and has a base of about 100 yards. This 
is one of a number of such deposits at the south end of the lake. 
At the railway works, Bungendore (south end), a well was sunk 
for water about 14 mile from the lake, in ground the surface of 
which would, I should think, be about 20 feet above the present 
level. There was 4 feet of earth on top ; then clean gravel to 28 
feet deep. There the abundance of water stopped the sinking; 
and 6 miles from the lake, though still on the flat land, which 
evidently is part of its ancient bed, a well was sunk, andnear the 
top of it gravel was found, and carried down to 18 feet, where it 
contained so much water that they could not sink any deeper. At 
the north end of the lake these conditions are found in duplicate 
almost exactly, only there the gravel ridges seem to be higher. 
The most recent of these gravel deposits at both ends of the lake 
abut on to the western mountains, and extend thence obliquely 
across the old lake bed, thus cutting off from the main body por- 
tions of it which are now swamps. The southern one, however, 
does not hold water well, while the northern one has always been 
known as the wet lagoon, because it always contained water until 
last year, when Mr. Beit succeeded in draining it. 
With reference to the height of these ridges above the water 
now, I was unable to take any levels at the northern end of the 
lake ; but at the south end I ran the level from the 1871 flood 
level to the top of the gravel ridge 197 feet, the rise being 22 
feet 8 inches ; thence down the other side of the ridge to the bed - 
of the swamp, descending 18 feet 8 inches in 93 feet; the old 
swamp bed is therefore only 4 feet above the 1871 level of the 
lake. I then took in eight places the difference in level between 
the present water and the 1871 level, and found the mean to be 11 
feet 11 inches on February 20 this year. The extremes of these 
