Since I'm heading to Launceston today, Here's a pic from last time I was there.
Bit of geology... three rivers meet in Launceston (well two rivers and an estuary really but let's not get too technical). All of them follow major cracks in the really hard dolerite rock through no fault of their own (geology joke). This spot is where the South Esk meets the Tamar River and becomes tidal. It's also the narrowest point in the Cataract Gorge and is quite a sight (and sound) when the river floods!
The holes in the rocks are caused by the roaring, swirling floodwaters, and debris, which in this spot is assisted by the water being pushed back by the incoming tide.
Apparently just down river a naturally formed rock ball around half a metre diameter was dredged from the water, that was a perfect sphere to within a couple of thousandths of an inch (that's half a bee's dick [0.5bd] in the Australian metric system).
So there you go. Water that is powerful enough to make holes in solid rock. Don't you just love geology?!
#launceston #gorge #myhometown