|Welford National Park||August 21 2021|
|A pause, around breakfast time, to wonder at the bark of
what we think may be, perhaps, coolabah trees.
|Then east, and south, through Jundah, to Welford National
Once out of Lochern Park, having crossed the Thomson River, the vegetation changes.
|We didn't stop to find out why Stonehenge was named Stonehenge.|
|But we enjoy the sealed road to Jundah.|
|Past Swan Vale Lookout. The road has climbed the jumpup.
There is what I thought a nice geological description of laterite formation, the cap that preserves the jump up, and the erosion around the edges. Repeated for my continued education below.
One day I'll look up silcrete and calcrete, which also cap jump ups.
This pic is looking west across the Thomson River vallley.
| From the interpretive sign at Swan Vale
lookout. With thanks to DCQ (Desert Channels Queensland).
Jump Ups are
a feature of both the Mitchell Grass Downs and the Channel Country. They can
form spectactular visual features on an otherwise monotonous horizon as the
traveller traverses the broad featureless plains common to this area of
Australia. Their elevation in a flat landscape provides wonderful vantage
points, with the landscape rolling away for as far as the eye can see,
exposing geographic features clearly.
These formations are the product of former geologic epochs. 220 million
years ago, the Great Artesian Basin was created when enormous tectonic
forces down warped the region which then began to fill with the sediments of
ancient rivers and lakes. The environment was more akin to that of the
Amazon Basin of today.
A series of shallow inland seas then flooded the continent. Over the next
twenty million years, the seas retreated north, leaving behind deep layers
of sand and mud which compressed into rock. It was these layers that
underwent heavy weathering and erosion carving the landscape we see today.
These processes also formed the world famous opals mined in the area.
With thin, rocky soils, these jump ups support flora and fauna ideally
adapted for survival in harsh environment. Spinifex can fuel spectacular
seasonal fires, either deliberately lit to clear dead plant material and
promote new growth, or as a result of lightning strike from summer storms.
Mulga is often twisted and distorted as trees scrabble in search of a
foothold and nutrition. After rains, the jump ups soften. Hardy shrubs like
cassia, turkey bush and senna burst into bloom. Water collects in deep rock
Abroiginal tribes passing through this inhospitable country carved native wells to conserve precious water for dry times. The rock holes become a focal point for birds and animals while the water lasts. Domestic stock rarely venture up these formations, so they form natural barriers creating a refuge, particularly for a wide variety of reptiles, for wallaroos and for dingoes. However they also create a haven for thousands of feral goats.
Further on a native well. Carved out of the rock, with drainage to it for when it rains.
There is water about 600mm down. We don't know how deep.
Nice to see it well preserved.
|At Jundah there is a nice sign outside the post office /
We were looking for info on Hellhole, but info was closed (Saturday).
The sign saves me the effort of drawing the rivers, as I did for Kakadu and surrounds.
This version came from "Ashley Murphy - Evolutionary Histories and Futures of the Fishes of the Lake Eyre Basin".
Also saves me a bit more research on where the watershed is between Gulf Country (north flowing rivers) and the Eyre Basin (south flowing rivers). The northern boundary is, as we thought, around Camooweal, Mt Isa and Duchess.
Welford National Park is in the triangle where Thomson meets Barcoo to form Cooper Creek.
Last night at Lochern we were camped on the bank of the Thomson. Tonight on the Barcoo.
|Once in Welford Nat Park we decide on the shortcut, the
"desert track" to the campsite.
Red sand and spinifex.
A little concerned as the track is not on our maps and the markers are designed around clockwise rather than our anti-clockwise approach.
|Past the Southern Cross Bore. Without its windmill.|
|Past an oil well. 1800m deep. Abandoned.|
|Welford is the west most extent of Simpson and Strzelecki
Desert dune systems.
Widely spaced and short here, almost non-existent.
But very red and old looking.
|We didn't find cane grass on the dune, as in the Simpson.
|Rather sparsely vegetated.|
|But we did remove a small sample of sand.
Roughly to scale, the sand samples collected in the Simpson Desert in 2017, and far right today's sample.
Hopefully not just my imagination, its darker. More oxidation, more iron oxide on the sand grains.
The sand moved from south to north. Today's dune is older.
I've yet to catch a sample from the north of the Simpson.
|The end of the dune, and the track across sand.|
|Labeled "desert waterhole". The northern branch of the Barcoo.|
|South of which the red sand is replaced with pale sand.
And no dunes.
We camp just a little further south. Litttle Boomerang Water Hole on another branch of the very braided, like all the other rivers we've seen recently, Barcoo River.
|Towards Hell Hole Gorge National Park||August 22 - 23 2021|