Why did we bring you here?
Apart from being visually very cool, the area is of historical significance.
The first ascent of the area, known as Prospect Hill, was in 1789 by Captain-Lieutenant Watkin Tench. In 1791 Governor Phillip started granting plots of land to emancipated convicts and in 1792 began the grants to officers of the New South Wales Marine Corps.
The site was also known to be a focal point for some of the earliest experience of resistance by the local Aboriginal people to the European Farms, led by Pemulwuy, for whom the neighbouring suburb is now named.
One Tree Hill
The Moreton Bay fig tree is said to be 150 to 200 years old and to have been planted as part of the landscaping of the original house called Grey Stanes, the home of Nelson Lawson. It can be seen from the posted co-ordinates. The neighbouring land development is called 'Nelsons Ridge' after Lawson.
Geology of the area
The basic geology of the area, is that of Early Jurassic or Middle Jurassic picrite (commonly referred to as dolerite) laccolith (a dome shaped igneous intrusion between rock stratum). Williams and Carr indicate that Prospect Hill is one of a number of Mesozoic intrusions "emplaced into the Sydney Basin sequence at the junction of the Triassic, fluvial Hawkesbury Sandstone and overlying shallow-marine Ashfield Shale".
There are numerous descriptions of Prospect Hill as comprising: prospect dolerite, or prospect teschenite, but quarrying over the years has revealed that the material is predominantly coarse grained picrite with olivine-dolerite and dolerite.
The locality comprises an area approximately 2.5 kms by 1.4 kms and rises some 60 metres above the surrounding local area. The associated rock stratum comprises Hawkesbury Sandstone and lacustrine Ashfield Shale (a member of the Wianamatta group of shales).
Wilshire described Prospect Hill as “an annular teschenite intrusion which has invaded the Triassic Wianamatta shale. The outer oval shaped part of the intrusion has discordant contacts and rises about 75 feet above the central part which is occupied by a sill approximately 250 feet thick and which is overlain by 20 to 70 feet of shale”.
The Prospect Quarry
The main industry in Prospect since the early days of colonisation has been the quarrying of blue metal. Local roads were paved with broken grey dolerite from Prospect Hill as early as the 1820s. In 1903 The Emu and Prospect Road Gravel and Metal Company was formed and the company bought Prospect Hill. The New South Wales Blue Metal Company bought the Prospect quarry in 1919 and after incorporation of a new company in 1921, the name changed to New South Wales Associated Blue Metal Quarries Limited. Due to the effects of the Great Depression, in 1935 the New South Wales Government sold many of their quarrying operations to a joint venture company called Quarries Pty Limited.
A marketing company called Blue Metal & Gravel Limited (BMG) was formed to sell the aggregate that came from Quarries Pty Limited properties. By the end of World War II, BMG had closed down all the quarries except for two that had the best class of basalt, Prospect quarry being one of the two. BMG began to diversify their operations in 1951, which resulted in a hot mix bitumen plant called Bituminous Pavements being established at Prospect. By 1978 the company that ran this operation was called Blue Metal Industries Limited (BMI). This company claimed to own and operate Australia’s largest and one of Australia’s most modern blue metal quarries on their Prospect holding, known as the Greystanes Estate. Boral Limited acquired BMI in 1982 and used the Greystanes site to provide administrative support for many of Boral’s companies.
Boral have since closed the quarrying operations and developed the site into a light industrial development, which you will be locted within when at the posted coordinates.
Information for this Earthcache was gained via information from The Heritage Trust and Boral.
Regarding the Earthcache
While standing at GZ, you will need to answer the following questions and email your response to the CO. You will also need to take a photo of yourself along the eastern wall of the Quarry, with One Tree Hill behind you and load it with your log. Feel free to register your "Found" log and the CO will contact you if required.
Questions
1. How many colours can you see along the eastern wall of the quarry? Why do you think these colours have formed?
2. Describe the textures you see within each layer of the wall? How have these textures formed?
3. How high (estimate) is the eastern wall cutting?
4. Optional: Upload a photo of you or your group and your GPS in the Quarry, with One Tree in the background.
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Did you know that NSW has a geocaching association? Geocaching NSW aims to enhance and improve the activity of geocaching and holds regular events where geocachers meet to enjoy their common interests. Visit the association website here. |