Mon 10th August.— Uluru-Kata Tjuta National Park. A good place to start the whole story: Uluru and Kata Tjuta are eroded remnants of sediment laid down in a vast basin around 550 million years ago, then tilted almost vertical by later mountain-building. It's roughly the same era as the Ediacaran seas that later preserved Sprigg's fossils further south, so it sets the scene nicely.
Wed 12th August — Coober Pedy. A geological detour from the Ediacaran story: opal here formed much later, in the Cretaceous, when silica-rich water percolated through sediments left by the inland sea that once covered central Australia. Worth knowing it's a completely different chapter to what you'll see in the Flinders — younger rocks, different process.
Thurs 13th August.— Oodnadatta Track, William Creek, Birdsville. You're crossing the edge of the Great Artesian Basin here — old inland-sea sediments again, this time functioning as a giant underground aquifer.
Fri 14th August.— Kati Thanda-Lake Eyre, Marree. Australia's lowest point, and a genuinely young geological feature by comparison — a shallow, ephemeral salt basin still actively forming today.
Sat 15th August.— Gammon Ranges National Park, Arkaroola. This is where it gets properly old: the Mount Painter Inlier around Arkaroola exposes some of the oldest rocks in South Australia, over a billion years old — older than the Adelaide Geosyncline rocks that host the Ediacaran fossils further south. And of course this is Sprigg's own patch of ground.
Sun 16th August. — Arkaroola, Wilpena Pound. Wilpena Pound is the classic Flinders Ranges image — a huge synclinal rock basin rimmed by Rawnsley Quartzite, part of the same folded sequence (the Adelaide Geosyncline) that preserves the Ediacaran fossils.
Mon 17th August. — Wilpena Pound, Ikara-Flinders Ranges National Park.This is where Brachina Gorge sits, so your geological trail day — driving through the exposed, tilted layers that record roughly 130 million years of that ancient sea.
Tue 18th August.— Clare Valley, Adelaide. More wine country than geology, a nice unwind after the Ediacaran deep-time immersion.
Wed 19th August. — Depart Adelaide — with the South Australian Museum an easy option if there's a gap before your flight, to see the original Dickinsonia and Spriggina fossils.
So the geological arc of the trip really builds: Uluru (550 Ma, tilted and eroded) → Coober Pedy (a Cretaceous digression) → Lake Eyre (young and still forming) → Arkaroola (over a billion years old) → Wilpena/Brachina (back to the Ediacaran story, now with the rock record laid open in front of you). Reading *Rock Star* and watching a PBS Eons episode or two before Day 7 would land well, since that's the day you arrive at Sprigg's own sanctuary.
The Adelaide Superbasin (previously known as the Adelaide Geosyncline and Adelaide Rift Complex) is a major Neoproterozoic to middle Cambrian geological province in central and south-east South Australia, western New South Wales, and western Victoria. It consists of a thick pile of sedimentary rocks and minor volcanic rocks that were deposited on the eastern margin of the Australian continent during the time of breakup of the supercontinent Rodinia (previously called 'Pangaea I'). The Adelaide Superbasin has been the subject of much research, as it contains geological evidence for the breakup of Rodinia; two Snowball Earth events (the Sturtian and Marinoan glaciations); the Neoproterozoic oxygenation event, the transition to mostly eukaryotic life; and the Ediacaran Fauna.
Nilpena Ediacara National Park. This will be west of us on Sunday 16th August when we drive from Arkaroola to Wilpena Pound Resort. It is where Sprigg found the first fossils of multicellular animal life. In 1946, Reg Sprigg noticed "jellyfishes" in the Ediacara Hills of Australia's Flinders Ranges,
The Avalon Explosion and the Ediacaran Period explained
The Ediacaran ran from about 635 to 539 million years ago, and the Cambrian from about 539 to 485 million years ago — so the boundary between them sits right around 539 million years (the officially pinned figure is 538.8).
Two details that will mean something on your trip: the Ediacaran is the only geological period named after an Australian place — the Ediacara Hills in the Flinders, where Sprigg found his fossils — and it's the first new period added to the geological timescale in over a century (ratified in 2004). Better still, the official global reference point for the base of the Ediacaran, the "golden spike," is physically located at Enorama Creek in Brachina Gorge. Since Brachina Gorge is on your itinerary, you'll be able to stand at the actual marker that defines the period for the whole planet. The gorge road is set up as a geological trail that drives you forward through time, from about 650 to 500 million years ago, so you cross from the Ediacaran into the Cambrian in the space of a few kilometres.
The boundary itself marks the Cambrian explosion — the moment Sprigg's soft, quilted creatures gave way to animals with shells, eyes and skeletons. Having watched First Life, you'll recognise the cast.
The Ediacaran-Cambrian Transition
The rocks in this region preserve what Charles Darwin called "Darwin’s Dilemma"—the sudden, unexplained appearance of hard-bodied animals in the fossil record.
The Ediacaran World (635–538.8 Mya): The fossils at Nilpena represent the "Secret Garden of Ediacara". This was a peaceful marine ecosystem dominated by flat, immobile, soft-bodied organisms that absorbed nutrients directly from the water or microbial mats. They had no eyes, no mouths, no skeletons, and no predators.
The Transition Cliff: Right at the boundary of the Cambrian Period (538.8 million years ago), this entire ecosystem completely vanished from the fossil record.
The Cambrian Explosion: The peace ended with the rapid evolution of mobility, hard shells, compound eyes, and active predation. The burrowing and hunting animals of the Cambrian literally tore up the stable microbial seafloors that the Ediacaran biota relied on, triggering one of Earth's earliest mass extinctions.
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