Simpsons Gap – Black-footed Rock-Wallaby

The ancient bed of the Peterman Range and the more recent Alice Springs Orogeny have had well over 350,000,000 years to wear away; and they pretty much have. The old sedimentary layers occasionally show above the red sands and the very hard quartzite will be around for many millions of years.

In one spot, at Simpsons Gap, there is a rubble of rocks at the base of the quartzite walls and here live the small macropod (kangaroo types) called Black-footed Rock-Wallaby. Most of the time our mid-day arrival and short walk is not interrupted by wallaby viewing. But this trip was different. Is was coolish for the Outback, probably only eighty degrees or so and there were half a dozen wallabies gambling in the rocks. They are widespread and not uncommon, just not usually out in the day time.

Here are a couple long-distance images of these small roos.

This is an example of the base rock from the very old Peterman Mountains. The sedimentary layers were laid down in an old sea, then compressed and lifted over the ensuing millions of years. The mountains themselves have eroded away, filling the huge Amadeus Basin and leveling off much central Australia. As is to be expected in sea bottom accumulation most of the layering was originally sand and when compressed became sandstone and even later it became the hard glasslike quartzite. It took millions upon millions of years…pretty cool huh.

The two images above are of adult rock-wallabies. They have become rock dwellers, perhaps to avoid dingoes. There are also kangaroos in the grasslands and on the beaches. Perhaps the most unique is the Tree Kangaroo group. Yup, they live and hop, up in trees in the tropical northeast and in New Guinea. The bird below is one of Australia’s many honey-eaters, the white-plumed honey-eater. It is a rather common bird species of the mallee and eucalyptus lands in the arid center of the country.

The image below is of a MacDonnell Range cycad. Cycads are ancient plants which as a group are course and spiny. As they developed this morphology as a protection from browsing dinosaurs, they are now dressed in a somewhat unnecessary suit of armor. This particular plant was along the trail into Standley Chasm, a quartzite-walled slot, or chasm, that was once filled with a seam/squirt/or oozing of light colored dolerite (now eroded away).

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