A funny thing happened on the way to Cooloola
Cooloola Beach is one of my favourites. It resembles the long, long beach on the eastern side of Fraser Island but with not as many people, less rubbish and few or no dingos to worry about. (I don't mean I'm frightened of dingos; I'm talking about the stress of seeing them lean and hungry, skulking around car parks in search of food because they're prevented from roaming freely in their natural habitat by overzealous interventionist policies by National Parks rangers.) I say 'less rubbish', but that was until last Sunday.
Maybe I should be calling it Teewah Beach. Cooloola refers to a large recreation area that extends from south of Rainbow Beach town to Double Island Point, down to the Noosa River and west to parts of the Great Sandy National Park where there are long-distance walks by dunes, open heathland, Banksia and Scribbly Gum woodlands, rainforest remnants and freshwater lakes. On one map I have, however, the northern half of this extensive sweep of beach is called Cooloola and only the southern part is Teewah. I've always called it Cooloola. Please put me straight if you know.
Following a couple of days in Rainbow Beach, we decided to return to Brisbane via Teewah Beach and the Tewantin ferry across the Noosa River. We accessed the beach along Freshwater Road from Rainbow Beach Road, and a most pleasant drive through the forest it was. But the beach looked vastly different from previous visits. Extensive mounds of pumice lay along virtually the whole of its 40 kilometres; there were large amounts of other debris ranging from small bits of plastic in a rainbow of colours to lengths of string to thongs, wooden flotsam and larger pieces of plastic. All in all, it wasn't pretty. Scum was the word that came to mind. On my beautiful Cooloola.
The beach had been badly eroded, too. The entrance to Red Canyon (below) used to be a gradual incline. Lots of Casuarinas lay uprooted and fallen on the sand. The foredune area had been inundated and in the undergrowth a wave of material extended along the highest tide mark. It reminded me of tsunami creep.
So, what was going on? Large ocean swells of up to 2.5 metres had combined with higher than usual tides (over 2 metres) over the weekend – and were expected to continue until midweek. The Department of National Parks (Recreation, Sport and Racing) issued an alert on Monday about conditions on the beach and in campsites. They estimated the pumice was up to 30 cm thick in places. There was another hazard to be negotiated on Noosa North Shore where much more coffee rock than usual had been exposed by the removal of sand. Fortunately, we were travelling down at low tide*.
Coolum Boardriders Club reported back at the beginning of April that they'd noticed a lot of pumice washed up on the beaches of both the Sunshine and Gold coasts as well as drifting offshore. They speculated that it had originated in underwater volcanic eruptions off Indonesia and in the western Pacific and had been carried south by ocean currents before being cast up on the beach by storm surges or large swells and tides. Some pieces had sea growths on them and others were quite round, suggesting they'd been around a while. While most of the pumice was light grey, some was black. Curiouser and curiouser.
The Queensland coast usually experiences damage to beaches during cyclones, when huge waves are generated by strong onshore winds. If large waves coincide with high tides then erosion is far greater. If a cyclone is severe, more than 400 cubic metres of sand per metre of beach may be removed and the beach recede by 50 metres.
But back to the pumice. I would like to know if there's been a pumice deposition like this before. And exactly where it's come from. And whether the Parks Department think it will gradually be removed back into the ocean. And whether all the sand eroded away will eventually be redeposited back on the beach or will visitors to Red Canyon need stepladders in future. I am on the case**.
Cooloola was, of course, still beautiful. But there was an awful lot of pumice.
* Get your tide tables here. And you cannot drive in Cooloola Recreation Area without a valid vehicle access permit.
** Post script: I contacted Queensland Parks & Wildlife Service, who were very helpful and consulted a coastal scientist on my behalf. He confirmed that pumice is commonly deposited on beaches. Local wind and wave conditions may result in concentrations on some beaches. The pumice may become buried in the dunes as they rebuild and then released during the next erosion event. There has been a lot of erosion in recent times in this region. On being shown the photograph of the dune scarp at the entrance to Red Canyon, he surmised that the pumice may well have come out of the scarp face. In the past he has seen pumice layers up to 150 mm thick in dune scarp faces.
This post was last updated on 1 June 2013