ALMOST DESTROYED
An Island and a Lake almost destroyed by man
kind. It does not matter whether it was from sand mining or rock
mining, Windang Island and Lake Illawarra have had their bad luck
overturned by Mother Nature.
LAKE ILLAWARRA
Throughout
recorded white Australian and passed-down Aboriginal history, Lake
Illawarra has been silting and flooding with its entrance being
covered by large volumes of ever-shifting sand.
There are hills to the north, west and south of the lake and sand
dunes to the east. Geologists estimate that the hills began forming
some 200 million years ago and that volcanic and uplift activity
continued until around 20 million years ago. Lake Illawarra is
located in the Macquarie Rivulet valley. The valley was drowned
approx. 6000 to 7000 years ago (Holocene Marine Transgression era)
when the sea levels reached what they are now. The sand dunes which
form the barrier between the lake and the ocean are the result of
much more recent sea level changes. Lake Illawarra is classed as a
“Barrier Estuary”. Barrier Estuaries have narrow
elongated entrance channels and broad tidal sand flats. It is also
the largest estuarine lagoon along the NSW coast. An
“estuary” is a partially enclosed coastal body of
water, partially saltwater, partially freshwater. It also must be
part tidal and part non tidal. Its unusual characteristic is that
despite a surface area of 35 square kilometres, it has a maximum
depth of only 3.5m with a significant area of the lake being less
than 1m in depth. The average lake depth is 1.9m. The Lake, being a
“Barrier” estuary, has a relatively long and shallow
entrance that was periodically blocked off. Due to the nature of
the sea entrance, very little tidal variation occurred in the lake.
Its freshwater catchment area covers 270 km2
Natural cycles at one point saw the lake entrance
not only open, but over 2.8 metres deep, allowing small sharks and
dolphins passage in and out of the lake.
Commercial sand excavation was undertaken along Warilla and Perkins
beaches from the 1940s to 1970s. The major sand dune along Warilla
Beach, next to today’s beachside car park, was excavated and
some of it’s’ product was even exported to Waikiki in
Hawaii. Extensive sand extraction of close to 500,000 tons annually
at Windang/Primbee around the early 1960s did in fact allow the sea
to breach the formidable Perkins Beach dunes at Kemblawarra.
WINDANG ISLAND
The
Illawarra coastline is dominated by steep rocky headlands, with
bays and some of the most pristine beaches in the world. A major
headland at Red Point (Port Kembla) divides the coast into two
morphologically distinct regions. North of Red Point region is
referred to as the Wollongong Embayment and the south, which
includes the Shellharbour area, is the Windang Embayment. Windang
Island and Stack Island (Minnamurra River) are the only significant
near–shore islands along the Shellharbour coastline. Both are
made of “Bumbo Latite”. This applies to all the exposed
bedrock along the coast between Shellharbour South Beach and
Minnamurra. Windang Island is joined to the mainland by a tombolo
which extended either from the northern or southern entrance bank.
The tombolo was part of the Windang barrier system.
WHAT COULD HAVE HAPPENED
The biggest risk to Lake Illawarra and Windang Island was by the
concept of creating a deep sea channel from near the present
“Tallawarra Power Station” site through Lake Illawarra
and out to sea. This was to be built using the rock from Windang
Island.
Sub littoral (below tide level) kelp forests exist around the
island. These forests are home to Ostracods. There is a minimum of
69 species recorded living in the kelp. A greater proportion of
Ostracods are the smooth-shelled forms occurring in the shallow
waters.
In 1895 The Illawarra Harbour and Land
Corporation Railway Line was commenced and an attempt was made to
link the proposed Lake Illawarra Harbour to the "Ocean Seam
Colliery". The railway line was to be 10.8 kms long from Tallawarra
Point, through Koonawarra to the main road and crossing over the
Illawarra Railway line to the colliery which was situated 500
metres west of the Old West Dapto Public School site. It
never hauled coal as the coal deposits when tested were found to be
unsatisfactory. Only the northern end of the Illawarra
Harbour and Land Corporation railway, apart from the Dapto Smelter
section, was ever used to haul paying loads. There are some
physical remains of this line still to be seen in Dapto.
If they had been successful, this haven for sea life would have
been destroyed. The jetty built on the western shore of the lake
was to allow the export of coal from the Ocean View/Seam colliery.
As part of this scheme, a channel was to be dredged through the
entrance of Lake Illawarra to allow ocean-going boats to reach the
lake jetty. The channel was to be 7.3 kms long and 131 metres wide
between the breakwaters at the lake entrance. A railway line was
built on Windang Island to carry rock cut from the south-western
side of the Island through to the mainland side of the Island. This
rock was used to build the breakwaters, the remains of which can be
seen today. The project was abandoned in 1902 because of the
problem of drifting sand blocking the lake entrance channel.
Mother Nature stepped in and saved a
“Sea Haven” that could have been lost
forever.
The railway line linking the mine with the jetty
opened in 1895 but closed in 1902, abandoned because of problems
associated with dredging the lake. The decision was then made to
make Port Kembla the coal loading point.
To complete
this Earth cache you need to email us explaining simply;
1. At GZ
the Bumbo Latite has a different appearance to the rest of the rock
platform. Describe the changed appearance and what you think has
caused these changes
2. Post a
photograph of your GPSr /yourself with a set of the old wheels from
anywhere in that area