A deteriorating wall in a 70-year-old quarry in south-western Victoria is currently the subject of some debate between the quarry owner and Victorian geologists.
Having not been in operation for around 44 years, Brown’s Quarry, near Warrnambool, has been used to dump clean fill by the owner, Rodger Constructions.
The site is part of an extinct volcanic crater named Tower Hill, which is believed to have erupted about 25,000 years ago, leaving behind some pristine geological samples.
However, Rodgers managing director Graeme Rodger has decided the site will now be filled in and revegetated, having served its purpose for long enough.
Rodgers told the ABC an exposed wall, which geologists had studied for decades, had been deteriorating for some time and that there wouldn’t be much left of it soon either way.
“Over the years that I’ve owned it, I’ve seen it probably reduce the top of the wall by about a metre and a half. The weather is just eroding it away and it’s collapsing into the quarry,” he told the ABC.
“I don’t know whether it’ll be five years or 50, but eventually that whole (quarry) wall could disintegrate and fall into the quarry and you’d have a big scallop out of that wall, which is the southern perimeter of the whole crater.”
Amongst those opposing the filling in of Brown’s Quarry is Monash University professor Raymond Cas, who has researched the geology at the Tower Hill crater for more than 30 years.
Cas said the exposed quarry wall was imperative to the ongoing understanding of the area’s geology.
“When you aggregate all the quarries it provides an almost 360-degree exposure of the volcanic deposits. If we only had one quarry, we wouldn’t have that perspective,” Cas told the ABC.
Another Port Fairy-based geologist Mike Raetz agreed the exposed wall, while requiring redress in terms of safety, was very important to scientific study and comprehension.
“The southern rim in this particular quarry has exposed some of the best examples of some of these very violent nuclear-style eruptions, the traces of which you can see as far as Thunder Point in Warrnambool,” he told the ABC. “Aspects of that volcanic history are differently preserved in different places, and Brown’s Quarry has some exceptional value in that regard.”
Rodgers remained adamant that the wall, first and foremost, is a public safety issue. “I am not prepared as a conservationist myself to a certain extent to walk away from this and have it all fall in,” he said. “There’s always middle ground, and if someone can show me the middle ground how to put a wall back and make it safe like that certainly I’d listen to them because it might be something I couldn’t possibly have thought of, but I doubt it.”
Old volcanic markings are common in quarries. Geologists also expressed concern about the fate of a diatreme in the former Hornsby Quarry before it was refilled. The diatreme has been preserved and is likely to be a feature of the rehabilitated site, as proposed by the Hornsby Shire Council.