There is a southbound back road out of Melrose, known as the Surveyor’s Road. It joins the main road again at Bangor, just before Port Germein Gorge cuts its winding westward way through the ranges. Hardly having left Melrose I was compelled to stop by a small, quarry-like site to the right of the road: Sand-ripple stone, a section of an ancient beach, once twenty feet long, now, twenty feet high, was gaping out from a cut hillock like a giant piece of cake.
Rock
I dug from this shallow soil
a rock-lump square as a book
split into leaves of clay.
A long curved wash of ripple
left there its fingerprint
one long-before-time lost day.
I turned a dead sea’s leaves
stand on a shore of waves
and touch that day and look.
Wright,J. ,”Schweigen zwischen Wort und Wort” , Berlin 1990, p.130
No rock could have been better than this one with its thick printed leaves to present a few lines on the history of the mountain range. Like an old book damaged by time, the uppermost “page” of straight, ruler-like sand ripples had been damaged. There were small holes in it and there were large sections missing of it, thus revealing parts of the “page” underneath, sand-ripple stone again, but this time with irregular ripples, shaped at a time of different currents. Cracks were running through those “pages” like the crinkly signs of wear and tear of a well used, old book.
The printing of that book “one long-before-time lost day” had happened sometime between 1100 and 570 million years ago. During that time, when ancestral Antarctica, India and Australia still belonged to one great land mass, movement in the earth’s crust caused the land now underlying the Flinders Ranges to sink. Cracks appeared in the earth’s crust resulting in volcanic activity, depressions appeared and slowly grew, thus forming a system of lakes and lagoons which filled with sediments and which had shore lines. During a period of about 500 million years sediments, i.e. mud, sand, lagoonal and glacial deposits, finally about 20 km thick were accumulated, part of which were later pressed up, to form the Flinders Range and their southern continuation, the Mount Lofty Ranges.
“Geological studies have revealed that the rocks which form the ranges were originally deposited as sediments between 1000 and 500 million years ago. They bear a record of ancient environments and life forms belonging to a period in Earth’s history which lasted for hundreds of millions of years.
Subsequent erosion has exposed these rocks and allowed geologists to probe their secrets. The gorges in particular, once the subject of dreamtime legends … provide pathways through the rock sequence which reveal their history-corridors through time.”
Selby, J., “Corridors Through Time”, p.1
My corridor through time, a section of sandripple-rock just outside Melrose, brought me onto an ancient lakeshore or some tidal flat, where wind and/or water had initially created the ripple-marks. The first layer of unregular ripples had been covered very rapidly by another layer of sand which wind or water had shaped into ruler-straight ripples, after which it had been covered rapidly by succeeding layers of sand. Compressed into hard rock, pressed up to form a hillock and cut in recent times like a slice of cake, two pages of a long book of history stood right in front of me.
However, not being a geologist, I knew only vaguely what chapter in earth’s history they belonged to, I could not put a precise figure to my corridor through time. I had no way of knowing whether these sand ripples had been formed before or after glaciers of the Sturtian Ice Age (720 million years ago) had covered part of the country around here or what kind of life really had existed in the lake against whose shore I was leaning. But I was excited by the thought that I could be right beside a shore whose waters had been home to Ediacarian fauna, the first living creatures known to man which developed brain-cells – very primitive ones but nevertheless brain-cells. And the first evidence of that life-form had been discovered less than 50 years ago, in 1946, by Ecologist R.C. Sprigg, now owner of the Arkaroola-Mt. Painter Sanctuary in the northern Flinders Ranges, as the crow flies only about 150 km north of Melrose. The importance of his find was that he had discovered a missing link of evidence in evolutionary history.
“No animal would appear less likely to be preserved down through the geological ages than a watery jelly fish. That such creatures did so, and died leaving highly detailed fossil impressions by the millions in sands some 600 million years ago is quite incredible.
It is indeed a fact of historic record that paleontologists, biologists and students of evolution. .. had long predicted that, late in Precambrian time jelly fish and worms just had to have been the reigning lords of creation …
In 1946, in the low hills of Ediacara, near the eastern margin of Lake Torrens, the forgoing ‘near geological impossibility’ did in fact materialise. In this remote place, I found the world’s first ever ‘Precambrian’ fossil jelly fish,… All existing animals were then soft bodied … when jelly fish dry out in the sun, they become tough and leathery despite their watery nature. If, in the absence of predators, … they were covered quickly by films of mud settling out from coastal flood waters, their impressions stood an even better prospect of being preserved. ”
Sprigg, R.C. “Arkaroola-Mount-Painter – The last billion years”, pp 137-38
Had the conditions near today’s Melrose been similarly favourable to allow such quick toughing up and mud-encasing of creatures that had scored a definite first in the development of nerve-tissue and its concentration at a ‘head’ like the Spriggina floundersi? Had the shores near Melrose also witnessed these “world’s lowliest worms”, that were already animals “with a brain, an ability to make decisions, however insignificant” (ibid, p 140)? So many questions and no answers. All I knew was that the advance of the sea, caused by the further sinking of the so-called Adelaide Geosyncline around 570 million years ago, brought with it a new stage of evolution, animals with hard skeletons.
