Rob Corkery, Honorary Fellow of the Institute of Quarrying, explains how a once vital quarry has been transformed into a major multipurpose recreational and environmental asset for northern Sydney.
After almost 100 years of supplying aggregates and road base to Sydney’s construction industry and numerous infrastructure projects, Hornsby Quarry closed in 2003.
Hornsby Shire Council purchased the 60ha site soon after its closure. However, the former quarry remained largely dormant until mid-2016. At that time, the quarry void extended approximately 120m below the surrounding land surface, and the overall area of disturbance covered around 30ha.
A turning point in the quarry’s transformation came in mid 2017 with the construction of the nearby NorthConnex road tunnel. Over a period of approximately 18 months, around 1.2 million cubic metres of sandstone and shale excavated from the tunnel were used to partially backfill the quarry void. This helped to reshape the landform within the quarry void and created surrounding landforms suitable for future uses, including playing fields, open space, and supporting infrastructure.
The Hornsby Shire Council began extensive community consultation, technical studies, and staged planning to turn the former quarry into a major multipurpose recreational and environmental asset for northern Sydney.
A park for the community
Hornsby Shire Council wanted to transform more than just the former quarry void. The Council’s plan for Hornsby Park included an additional 30ha of surrounding land, previously part of the quarry’s environmental buffer.
The vision for the site includes a blend of active and passive recreation opportunities, namely:
- Playing fields and open parkland
- Picnic areas and community gathering spaces
- Scenic lookouts into the former volcanic structure
- Walking and cycling trails
- Environmental and educational precincts
The development of Hornsby Park has also drawn upon the knowledge of those closely connected to the quarry’s operational past. Former crushing plant operator Peter Milgate, who worked on site for nearly 30 years, contributed valuable historical insight into the Crusher Plant Precinct. The development also benefited from input provided by the quarry’s final manager, Roger Moona.
During its operational life, rock was extracted by blasting and transported to a crushing and screening plant located on the southern side of the quarry. Today, this industrial history forms an important part of the site’s character and interpretation.
Hornsby Quarry was centred on a Jurassic volcanic diatreme, comprising predominantly breccia, with some basalt and dolerite. One of the most remarkable features of the site is the exposed upper section of the diatreme on the eastern face of the former quarry. This striking geological cross-section reveals the internal structure of the collapsed volcanic system which has been the reason for the former quarry being recognised as an internationally significant geosite.
The geosite lies within the Ku-ring-gai GeoRegion, a designated area of geologically important locations across northern Sydney. In collaboration with Hornsby Shire Council, the Ku-ring-gai GeoRegion Steering Committee, with valued input from John Martyn, has contributed to the development of interpretive and educational materials to support visitor understanding and school-based learning.
The geosite also highlights the connection between the volcanic geology and the surrounding area’s ecology, particularly the critically endangered Sydney Blue Gum High Forest, which is closely linked to the fertile soils derived from the diatreme.
A grand opening
Stage one of Hornsby Park was officially opened on 28 March 2026 marking a major milestone in the long-term transformation of the former quarry.
The opening involved a joint ribbon-cutting with the Mayor, Councillors and Anna Watson MP representing the Hon Ron Hoenig MP, Minister for Local Government. Mayor Warren Waddell said, “the opening of the first stage of Hornsby Park was an important step in delivering a long-held community vision.”
The first stage includes the restored Crusher Plant Precinct and a cantilevered Southern Lookout, offering expansive views across the former quarry. Visitors can now enjoy picnic shelters, barbecue facilities, parking for vehicles and a network of trails. These include three sets of upgraded historic steps, originally constructed during the 1930s, an enduring link to the site’s past.
Delivery of the Crusher Plant Precinct was supported by the NSW Government through a Stronger Communities Fund grant. Further stages of Hornsby Park are currently under construction and will be delivered progressively. These include the quarry loop walking and cycling track, additional scenic lookouts, a bike jump and pump track, and the Old Man’s Valley field of play. As each stage is completed, the park will continue to evolve into a significant regional tourism and educational destination.
The transformation of Hornsby Quarry into Hornsby Park is an excellent example of how former extractive industry sites can be reimagined for community benefit ensuring that the site continues to serve and add value to the community for generations to come. •
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