Fossil Coast Geo Travel Guide Explores the Ediacara Hills of Flinders Ranges South Australia

Fossil Coast’s Geo Travel blog series explores the Ediacara Hills of the Flinders Ranges in South Australia (31° 19' 52'' S 138° 38' 07'' E). This location is among the “First 100 Geological Heritage Sites” worldwide designated by the International Union of Geological Sciences (IUGS) in 2022.

Ediacaran Period Yorgia - Image by Aleksey Nagovitsyn

Are you looking for some travel inspiration or a reason for your next adventure? Do you consider yourself a traveller who likes to go a bit further afield? maybe off the beaten track?, or are you someone who enjoys visiting places for their geological and fossil heritage?

So sit back with a gin and tonic, maybe inspired by a bush gin, and enjoy this excursion to Australia.

South Australia is the southern, central state of Australia and is among the most rugged and driest outback wildernesses on the continent.

Similar in size to France and Germany combined its land has vast plains, low uplands, and extensive salt and clay-encrusted lake beds that rarely contain water.

At the heart of South Australia is the country's very own wine capital Adelaide whose 18 internationally renowned wine regions rank alongside Bordeaux in France, Napa Valley in the USA, and Bilbao Rioja in Spain.

Barossa Valley wine region of South Australia

One way to enjoy the natural outback beauty of South Australia that takes in the landscape of Flinders Ranges is by a road trip called the Explorers Way.

A 3,000 Km journey from Adelaide to Darwin that initially takes you through South Australia’s wine regions before navigating the Flinders Ranges and onwards north into the outback.

The Flinders Ranges are named after Matthew Flinders who mapped the entire South Australian coast in 1802. They are the largest discontinuous mountain range in South Australia composed largely of folded and faulted sediments dating back over 600 million years and are one of Australia's most significant natural sceneries.

Flinders Ranges national park of South Australia - Image by Zetter.

This semi-arid mountainous landscape is the traditional land of Australia’s first people known specifically as the Adnyamathanha People translated as “Rock People”. They are recognised as the native title holders of the Flinders Ranges under Australia’s Native Title Act 1993.

The Adnyamathanha People have an intricate and spiritual relationship with the land, plants, animals, and Awi Urtu, or ephemeral streams and waterholes of the Flinders Ranges. This relationship is called Yura Muda the Adnyamathanha people's belief in creation.

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The Flinders Ranges represents a period spanning 350 million years of geological successions providing an “archive” into the major stage of Earth’s history described as the “dawn of animal life” including the Ediacaran Period between 635 to 541 million years ago.

This was the time before the "apparently sudden appearance of complex animals in Cambrian rocks" described by Charles Darwin in his 1859 publication, "The Origin of Species".

This work is still considered to be the foundation of evolutionary biology and the basis for the scientific theory that populations evolve over time through successive generations by the process of natural selection.

These rocks provide a record of exceptional depositional, tectonic, and geothermal history in a subsiding geological basin known as the Adelaide Geosyncline or Adelaide Superbasin including the geological successions of the Ediacaran and Cambrian Periods.

The Ediacara Hills are part of the Flinders Range located 650 km north of Adelaide. This is a range of low hills in the northern part of the Flinders Range known for being the location of significant Ediacaran Period fossils.

The name "Ediacara" comes from an Aboriginal language expression meaning "veinlike spring of water". The Ediacara Hills give their name to the Ediacaran Period also known as the Vendian Period.

Ediacaran Period fossils are synonymous with the Australian mining geologist named Reginald C. Sprigg who in 1946 whilst exploring the old Ediacara minefield on the Flinders Range. He found fossil impressions or trace fossils within the coarse-grained sandstone known as the Pound Subgroup of the Wilpena Group and Heysen Supergroup.

The Pound Subgroup is an on and off-shore folded belt of red-brown, thin-bedded sandstone and quartzite with shale casts. This subgroup is considered to be a shallow-marine to deltaic succession with the Ediacaran fossils found in the sandstone facies.

This layer was influenced by the Delamerian Orogeny or mountain-building event that created westward-verging folds and thrust faults from the immense stresses transferred at the time from the trailing edge of the newly assembled Gondwana supercontinent.

Flinders Ranges North of Hawker, South Australia - Image by Michael Skopal

A locally found Ediacaran Period fossil called Spriggina floundersi become the official fossil emblem of South Australia in 2017 and is named after both Reg Sprigg and an amateur South Australian fossil hunter called Ben Flounders. A statue of this organism was unveiled at the University of Adelaide in 2020 recreated in Paris Creek marble by well-known South Australian sculptor, Silvio Apponyi, OAM.

“This sculpture not only highlights South Australia’s unique geological heritage, but also the University of Adelaide’s proud history of research excellence in geology that continues today, and the contributions made to this heritage by many notable University alumni and staff,” says Acting Vice-Chancellor Professor John Williams

One of the best places to see a collection of preserved fossils from the Ediacaran Period of the Flinders Range is the South Australian Museum in Adelaide.

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The rocks of the Ediacara Hills of the Flinders Range are a good example of a Lagerstätte. This is a German term that describes where layers of sedimentary rock show well-preserved fossils. These animals were buried in an anoxic environment with minimal bacteria activity.

The Ediacara Hills in the Flinders Ranges of South Australia is one of the best exposures of a complete succession of well as preserved soft-bodied multicellular Precambrian fossils with the appearance of major new body plans.

These animals lived and fed upon the nutrients of the sea bed's thick microbial or algal mats. They also predate the Cambrian Explosion triggered by the time of the Great Unconformity.

Parvancorina - Image by Masahiro Miyasaka

Up to 80 new life forms of Ediacara Biota have been documented including the Parvancorina, Rugoconites, Spriggina, Dickinsonia, Tribrachidium, Kimberella, Charniodiscus, and Yorgia.

Parvancorina or "small anchor" lived on the Ediacaran seafloor as a suspension feeder and grew up to 3 cm often pointing in the direction of the oncoming current. Interestingly, there has been a suggestion, though not proven, that Parvancorina was an arthropod ancestor to crabs and shrimp.

Rugoconites were circular to oval and grew up to 6 cm in diameter. Surrounded by a frill of tentacles and had a slow-moving or sessile lifestyle.

A Spriggina had a bilateral symmetry in that it has both a head and a tail. Its crescent-shaped head was attached to a tapering segmented body growing up to 5-6 cm in length. The upper surface is believed to have been covered in overlapping cuticular plates and the underside was covered with two rows of tough interlocking plates.

The Dickinsonia is one of the largest Ediacaran Period organisms. They were oval in shape and could grow up to 1.5 meters in length. Described as the best-studied of all Ediacaran organisms but also one of the most controversial. Their precise position within the animal tree still remains uncertain. It is thought they lived off the nutrients from the underlying microbial mat covering the sea bed.

Yogis had a low and segmented body consisting of a short wide "head", no appendages, and a long body region, reaching a maximum length of 25 cm.

The Tribrachidium was an immobile disc-shaped Ediacaran Period organism living on the sea bed. They are recognisable because they have three arms that appear to uniformly spiral outwards from their center. These are often found in large groups.

It is also noteworthy to consider visiting Enorama Creek in the Ikara-Flinders Ranges National Park. This remote place has the only international golden spike in the Southern Hemisphere. The golden spike officially recognises this location as a Global Stratotype Section and Point (GSSP) marking the end of the Elatina glaciation and Cryogenian Period and the start of the Ediacaran Period.