Christmas Bells

Christmas Bells
Christmas Bells - Blandfordia nobilis

Tuesday, June 26, 2007

Butler's Swamp - one mystery solved

The hills of Kangaloon have been oozing water, like never before. Robertson has apparently had its wettest June since 1950 (as has Sydney, too).
The flow from
Butler's Swamp.
A few inches deep,
and one can step over it.

As a result of all that rain, Butler's Swamp was flowing water from its lowest point, following just a "top-up" of a mere 5 mm of rain the day before. This sedge-grass swamp, over a peat base, fills to capacity, when everything is saturated, and then, very, very occasionally, it will overflow its reservoir, and water flows out through the sedge grasses.
The photo shows that we are actually beyond the peat base of Butler's Swamp at this point, for in you enlarge the photo you can see quartz pebbles in the base of this "stream" - sure indication that we are over sandstone, not a peat base. But the area is wet enough from soakage through the soil, to support classic swamp plants.

When the overflow runs out of the shrubbery, it crosses across the black soil area which the SCA is using as an access track (beside Tourist Road).
You can tell by looking at the shallow depression in the track, that this is not a regular stream, just a brief "overflow", for otherwise the track would be having to jump over a small gully. But no, not at his point, beside the pipeline - there is just a shallow depression, which the contractors have spanned with an informal arch of the pipeline, supported by a couple of offcut pieces of pipe. The track is normally dry, and cars have been known to drive over where this "stream" is flowing - without there being any need for a "creek-crossing".
On Sunday, there was a tiny flow, a mere trickle of water, flowing out across these tracks, and down beside the road. It was this small flow of water which I noticed, and which I traced back to its source. Sure enough, Butler's Swamp was flowing.

From a botanical point of view, you can tell from the little low-growing Grevillea (the dark green plant through which the stream is flowing) that this is not a permanent waterway. This Grevillea is a typical plant of the dry Sydney Sandstone habitat. It is NOT a water plant. The Lomandra rushes (thin strappy-leafed plants) are plants of damp areas, but the Grevillea is definitely not, as any home gardener will attest - they hate wet feet.
So, this photo is taken on the margin of sandstone soil and wetter soil - hence both types of vegetation growing within a single camera frame.

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