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Hinze dam is not named for Russell Hinze who was a Politian around the time it was started. The dam is actually named after the Hinze family which settled the area and owned the majority of the land the dam covers, however Russell is a relation to the original family.
Hinze Dam is a loose rock and concrete wall consisting of 5 million tonnes of local greywacke rock and half a million tonnes of local clay. The dam crest is 108.5 meters above sea level and can hold 309,700 million litres of water. It was built in 3 stages over nearly 50 years. It captures water from the Nerang river.
A wacke generally consisting of poorly sorted angular grains of quartz, feldspar and lithic fragments set in a compact clay-rich matrix. It is commonly formed from sediment deposited in submarine avalanches or from strong turbidity currents creating mixed-sediment slurries. They are often found on the edges of continental shelves or at the bottom of oceanic trenches. An old rock name that has been variously defined but is now generally applied to a dark grey, firmly indurated, coarse-grained sandstone that consists of poorly sorted, angular to sub angular grains of quartz and feldspar, with a variety of dark rock and mineral fragments embedded in a compact clayey matrix having the general composition of slate and containing an abundance of very fine-grained illite/sericite, and chlorite. Greywacke is abundant within the sedimentary section, esp. in the older strata, usually occurring as thick, extensive bodies. It generally reflects an environment in which erosion, transportation, deposition, and burial were so rapid that complete chemical weathering did not occur, as in an orogenic belt where sediments derived from recently elevated source areas were poured into a geosyncline. Greywackes are typically interbedded with marine shales or slates, and associated with submarine lava flows and bedded cherts; they are generally of marine origin and are believed to have been deposited by submarine turbidity currents.
Looking around the carparks and minor rock walls, the greywacke has quartz inclusions in the form of veins. Facing the west from the buildings (shop, education centre) there are steps cut into the hill side which is more likely where the rock was sourced.
As this is an Earth cache you must answer the questions below and send the answers to the CO.
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Why do you think the clay was included in the centre of the wall?
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Why is the clay covered by rock?
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Does the Greywacke rock appear hard or soft and crumbly, keeping in mind the surrounding rock walls are all Greywacke?
Message the Cache owner via the Message centre with the answers. Once the answers are sent it is ok to log as found. If there are issues with your answers the CO will get back to you. Feel free to include photos.