YABBA FALLS is one of the highest waterfalls in southern Queensland. There are two major plunges, this being the first 80m of its 160m descent into the Baiyambora Gorge.
THE DISCHARGE of this stream varies. Two months previous the whole of the algae covered wall was covered by falling water. Eight months earlier the stream was in major flood and the entirety of this section of the gorge was overwhelmed. In fact, my perch previously was known as Eye of the Needle for a massive rock sat above my eerie, wedged on the precipice edge, the result of an earlier flood in 2013. But the 2022 flood displaced the massive rock and has carried it way downstream and is yet to be located.
THE GEOLOGY is metamorphosed mudstone (of the Marumba beds). The mudstone is derived from colloidal clays deposited in a submarine graben, and those clays are in turn derived from volcanic rocks (probably andesite). The Marumba beds occur as a block of highly immature Early Permian marine strata. This geological unit is exposed within a thrust sheet on the western flank of the North D'Aguilar Block. Here it is mudstone (elsewhere, sandstone, siltstone, matrix-supported pebble to cobble conglomerate and occasional basaltic volcanics). Their age is constrained by poorly preserved marine macrofossils. All these beds were uplifted, folded and moved in significant thrusts during the Late Permian Hunter-Bowen orogeny - a major mountain building phase in eastern Australia. (References: Renata Sliwa, Rod Holcombe, Ian Stehbens, Warwick Wilmott)
The receding of these falls is along the line of a significant regional joint plane.

Tags:   Yabba Yabba Falls waterfall scenic reserve Top Plunge mudstone Marumba beds metamorphic abseiling Imbil Jimna Yabba Link national park algae precipice escarpment sheer Baiyambora Gorge joints faults volcanic legacy changing surface of the earth

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