The Underground Stream

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The smooth surface granite boulders covering the path of the underground stream, polished by years of rushing water.

The underground stream at Girraween National park is one place I didn’t get around to exploring until now, in mid winter. Its still rather warm though in the high teens, from what I hear, not too far off the pants summer weather back home. Spring is just around the corner and the spring flowers are what this national park is renowned for aside from its massive and curious granite features. The underground stream flows over a vast expanse of flat granite which has been eroded over tens of thousands of years into smooth polished curves and bowls where once just a thin crack existed. Huge boulders have broke off the face of the granite cliff face and the stream disappears beneath these but has eroded and polished away enough rock to climb through. The stream is no more than ankle deep now but walking through the forest to the along side the stream many small trees and shrubs were laid flat and bundles of twigs and grass hung in the tree a good meter or more above head height, a sign of how high and fast the water was rushing through at the peak of the flooding in January this year. Huge areas of grass and shrubs growing in the thin soils on top of the granite were rolled up like giant Swiss rolls by the force of the water.

The surface of the polished granite appears like leather compared to the coarse greyish unpolished stone. Lichens and minerals stain the under side of the granite shelf like a giant wave frozen in time.

The path into the park. The bracken browned by frosty mornings.

Granite boulders among the bush and  the peeling bark of a Gum tree.

Curved forms of the granite where Bald Rock creek first starts to carve its way down through the granite and a water fall where the stream disappears beneath the fallen boulders.

There are many large bowls which are carved out larger and larger during each flood by rocks caught up in the eddies within them which rush around like a washing machine. The bowls and the rounded rocks within them have a fancy geological name but whatever it is it has long since slipped from my mind.

A curiously unnatural feature. I guess it is where the huge expanse of granite, which was created by the slow cooling of a giant under ground magma chamber, cracked and was filled by subsequent lava. Don’t take my word for that.

Leionema rotund folium (Round-leaved phebalium) and Mirbelia speciosa subsp. Speciosa (Showy Mirbelia).

Because of the intermittent rainfall and subsequent intermittent flow of Australian streams and river, they form a series of interlinked pools and marshes rather than a continually flowing channel. That is, at least before the intervention of man clearing the forests and dredging and damming the streams to make the most of every last drop of water in a drought. Sheltered by the forest and stained by tannins these pools create some beautiful reflections.