bably assisted in this work 'by the dia¬ 
base ridges raising tbo land over where 
now run tile Mount Bruuy range and 
the land over Fluted Cape to a higher 
level than the land in the centre. 
These streams have pushed their tribu¬ 
taries right to the eastern edge of the 
island on the clnl' faces, and well to 
the south also. They have captured 
all the drainage of any rills that Mow¬ 
ed seaward over the cliffs, and have 
carved the landscape into a basin around 
their heads, with its rim and highest 
edge running round the cliffs on tho 
east and south, and along (lie Mount 
Bruny range on the north. Out of this 
basin ridges and points of diabase rise 
where the streams have not completed 
their work of removing the harder rock. 
These streams are still in the juvenile 
stage, but haw cut well below the 
ground water level, and are good per¬ 
manent flows of water, cutting into 
rocky beds with many waterfalls, and 
running in steep-sided gullies. 
There is ample evidence at the month 
of these rivulets of a recent change 
in land or sea level. Each flows from 
its narrow mountain valley out on to 
a flat alluvial plain. The old sea ed.'te 
can be traced passing inland some dis¬ 
tance in large bays, the position of the 
shores of which can lie traced where 
the hillsides rise steeply from the flats 
surrounding the mouths of the streams. 
Tnto these bays the rivulets have car¬ 
ried much sediment. 'Later the land 
has risen some 2i to b() feet, or the sea 
has sunk to the same amount, and these 
accumulations of sediments have been 
left bare as delta-shaped flats filling the 
bottoms of valleys that were. ap]iarent ly. 
bays of the seashore. Then the streams 
winding across these fertile flats with 
many a loop and bend have out down 
ten or more feet to the new level of 
the sea. and the winds from the north 
have piled up new sand dunes .across 
the levelled front of the-new seashore. 
By the south-eastern end of the 
lagoon that forms the mouth of Cook’s 
Rivulet can be clearly seen a line of 
old sand dunes, now half a mile inland, 
and covered with a layer of peat, on 
which heaths, grasses, and flowers arc 
growing to-day. These sand dunes 
are formed by the action of 
the tides and estuary currents, 
which wear away the prominences 
of the coastline as they surge past, 
and deposit the grains of rock in the 
quiet bays, where their speed Is check¬ 
ed. The wind catches the sand grains 
where the waves leave them, and piles 
up the great dunes which fringe all 
our coastal hays. The wind can drive 
these dunes inland, spreading desola¬ 
tion over the most fertile country, and 
the only protection for land behind 
dunes is a good binding of living vege¬ 
tation on the dunes. The greatest care 
must he taken never to destroy vege¬ 
tation on a dune, as the smallest gap 
may let the sand through to the destruc¬ 
tion of the farms behind, and there is 
nothing more difficult to stop than a 
moving sand dune. Fortunately, in 
Quiet Corner, sheltered from severe 
winds, tile sand dunes do not appear 
to he dangerous. 
The narrow neck which joins North 
and South Bruny is probably merely a 
sand dune formed by the deposition of 
sediments carried by the tide into the 
bay where it was originally cheeked 
in its flow between the two land 
masses of the north and the south 
island by the drag of the neighbour¬ 
ing shores and by the shallow water 
between. The tide gradually filled up 
this shallow water, and the wind raised 
the dunes of the Neck, which are held 
in position by vegetation, but prevent¬ 
ed from growing higher by the action 
of the wind. It is possible that a 
severe change in tidal or ocean currents 
would destroy the narrow connection. 
