A planet-defining point

In the dry creek bed of Enorama Creek, deep within Ikara-Flinders Ranges National Park, a small brass disc is set into the rock. This marker, known as a "Golden Spike," is a Global Boundary Stratotype Section and Point (GSSP). The International Union of Geological Sciences (IUGS) ratified this specific point in 2004, using it to officially define the start of the Ediacaran Period. This was the first new geological period added to the official time scale in 120 years.

The spike marks a precise boundary in the geological record dating to 635 million years ago. It sits at the base of a pale buff-colored layer of dolostone called the Nuccaleena Formation. This layer is a "cap carbonate," a distinctive type of rock deposited in warm, shallow seas as the planet rapidly warmed after a global ice age. Directly beneath this cap carbonate are glacial deposits of the Elatina Formation, evidence of the Marinoan glaciation when ice sheets may have covered the entire planet. The sharp transition from glacial debris to warm-water carbonate provides a clear, globally recognizable signal of the end of the Cryogenian "Snowball Earth" and the beginning of the Ediacaran. This is the only GSSP in the Southern Hemisphere.

The dawn of animals

The climatic shift marked by the Golden Spike set the conditions for a biological revolution. With the ice gone, oceans became more hospitable, and after millions of years of microbial dominance, large, complex, multicellular life appeared. These organisms, known as the Ediacaran biota, were mostly soft-bodied, leaving their imprints on sandy seafloors.

Fossils of these strange life forms were first found in the region in 1946 by geologist Reg Sprigg in the nearby Ediacara Hills, which give the period its name. The Flinders Ranges preserve an record of this early animal ecosystem. Discoveries include Dickinsonia, a flat, segmented organism that could move and absorb nutrients from the seafloor. There was also Spriggina, an armored, segmented creature with a distinct head, possibly an ancestor of arthropods. Frond-like organisms such as Charnia were once thought to be plants but were actually animals fixed to the seabed. These fossils represent Earth's earliest known animal communities, which flourished for nearly 94 million years before vanishing at the beginning of the Cambrian Period.

Practical Information

Opening Hours

The Ikara-Flinders Ranges National Park is accessible year-round, but the Brachina Gorge Road to the spike site may close after heavy rain. The best visiting seasons are autumn and spring.

Admission

A vehicle entry permit is required for the park.

Accessibility

The site is in a remote gorge. Reaching it requires a walk into a dry, rocky creek bed. The Brachina Gorge road is unsealed and best suited for 2WD vehicles with good clearance or 4WDs.

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First New Geological Period in 120 Years

A planet-defining point

The dawn of animals

💡Fun Facts

References

There's more in the app

Practical Information

First New Geological Period in 120 Years

A planet-defining point

The dawn of animals

💡Fun Facts

References

There's more in the app

Practical Information

Nearby curiosities

Nearby curiosities