Written by Leah Furey
The Pilliga’s rugged and remote landscape is unlike anywhere else in Australia. The largest remaining native forest on the Australian continent – with stunning sandstone escarpments and surrounding mountains – is rich in cultural and environmental significance.
But it’s the geographical history of the region that truly reveals how the landscape formed and how it has become an Australian Biodiversity Hotspot – one of only fifteen officially recognised by the Federal Government.
Taking to the trails for the Pilliga Ultra will give you a deep appreciation for this landscape and a chance to connect to a place that is both fragile and unique – and needs our protecting.
Sandstone & Volcanos
The foundation of the entire Pilliga Forest is the sandstone which was formed around 150 million years ago. Layers of sediment were laid down in a series of shallow freshwater lakes that were typical of the entire eastern region of Australia. As dinosaurs walked the earth, the beginning of the Pilliga as we know it today were formed.
As the sand compressed into rock, the Pilliga became flat sandstone country only broken up by shallow valleys and creeks. The region then experienced a period of volcanic activity which added the hills and undulations of the landscape – and eventually led to the creation of fertile floodplains.
About 17 million years ago there were scattered flows of basalt – followed by numerous explosive eruptions a million years later. The two main volcanoes active at this time were Warrumbungle and Kaputar – which covered much of the region with lava flows.
Since the end of the volcanic period about 13 million years ago the landscape has been slowly weathered to reveal the rocky outcrops, caves and unique shapes and colours in the rock that can be viewed today.
Image: Hilary McAllister
A Vital Resource Below Ground
The Pilliga sandstone is more than just an iconic landscape – the sedimentary layers that were deposited millions of years ago form the south-east corner of the Great Artesian Basin (GAB).
The GAB is Australia’s most significant hydrogeological system – and one of the largest artesian freshwater basins in the world. It extends underground from Cape York to Dubbo and covers over 1.7 million square kilometres.
The GAB is a vital water source for humans, animals and the environment. The Basin’s springs and wetlands support a range of ecosystems – and the water holds significant cultural, social and spiritual value to First Nations communities.
Basin water emerges through cracks in the rock and flows into springs, creeks and rivers – creating a permanent water source even during dry periods. It also supports local communities by providing town water and sustains agriculture, tourism and other industries.
The Pilliga Region’s Important Role
The Pilliga region plays an important role as a ‘recharge area’ for the groundwater system. Located at the edge of the basin, it is an area where rain water enters the GAB via underground aquifers and replenishes the underground stores.
Just like in a river catchment, the protection of water quality in a groundwater recharge area such as the Pilliga is of critical importance not just to the local environment, but to the whole underground system.
Read Part 2 of ‘The History of the Pilliga’ here.
