Biodiversity Strategy - Gosford City Council - NSW Government

Newcastle and forms a major barrier for fauna corridors to the west as well as dividing the
coastal parts of the City from the mountain districts.
The Central Coast enjoys a rich diversity of native wildlife and terrestrial and aquatic habitats.
For example, over 130 threatened plants and animals are found in the local government area.
The high number of threatened taxa reflects the area’s diverse natural habitats. Like other
coastal areas within close proximity to major cities, the region faces strong development
pressures with a resulting decline in biodiversity. Urban areas can support native biodiversity
and at the same time have enhanced quality of life for residents and visitors.
Despite the relatively large reserve areas and Council’s Coastal Open Space System many
natural areas are not protected. Options need to be explored to conserve important bushland
remnants and biological diversity across a range of land tenures including private land
ownership. These are real and pressing reasons to engage the community in adopting
behaviours that help protect biodiversity and maintain the qualities of living on the Central
Coast. Strategies aimed at reducing pressure on endangered/threatened species through the
rehabilitation of selected corridors to join up remnants (as a part of a biodiversity plan), will
benefit the Gosford local government area environmentally and aesthetically. The long term
result could provide a huge potential for the city in terms of ecotourism and increased land
values.
A - 4.2
Geology
Gosford City’s geology formed nearly 300 million years ago in the geological period known as
the Permian period. At that time, Sydney lay at the mouth of a broad swampy river basin
covered in lush plant life ferns, ginkos, primitive conifers, seed ferns, horsetails and trees of
Glossopteris. Around 230 million years ago at the beginning of the Triassic period, rivers eroded
the inland mountains and began depositing enormous quantities of sand, silt and clay to coast.
The sediment layers buried the Permian swamps (these turned into organic coal layers around
Sydney and Newcastle) and the sediment layers were compacted into coarse sandstone
(Hawkesbury sandstone). The lower layers of finer silts and clays formed mudstone and shale
to became the Narrabeen group of sandstone and shales. The sandy middle beds became
Hawkesbury sandstones and the uppermost and youngest strata of compressed silt and clay
became Wianamatta shales. By the end of the Triassic period, 190 million years ago, sediment
accumulations almost stopped. However, Australia was still part of Gondwana supercontinent
and pressures began to split the continent. In the Sydney Basin the initial movements were
marked by explosive eruptions of small volcanic breccia pipes of diatremes through sedimentary
rock (such as at Dillons Farm in Brisbane Water NP).
As the continents slowly separated over the next 140 million years there was a movement
upwards which formed the Blue Mountains, and a lowering along the faultline of what is now the
Hawkesbury Nepean River resulting in the Cumberland plain. Over 50 million years of the
Tertiary period rivers cut deep gorges through sandstone. Uplift occurred and gave rise to
outcrops of Hawkesbury sandstone. In the last 1.8 million years Quartenary alluvium continued
to accumulate.
During the Pleistocene ice age the sea level was 100 metres lower than it currently is.
Consequently, the mouth of the Hawkesbury River was further east of its present location.
There was subsequent melting of the ice caps and the associated sea level rise led to the
Hawkesbury River 'drowning'itself resulting in Broken Bay and Brisbane Water. The coastal
lagoons were also formed at this time. Minor adjustments have occurred since with perched
dunes formed as a result of wind blown sand, an example of this is the sand on the tops of
coastal cliffs in Bouddi National Park (Fisher 1997).
Biodiversity - Technical Report Page 82