Introduction

Along the western shore of Lake Clifton in Yalgorup National Park, roughly 90 kilometres south of Perth, a reef of thrombolites extends for six kilometres along the shoreline. Each structure is a rounded mass of calcium carbonate built up over thousands of years by communities of living cyanobacteria. These are not rock formations that happen to look organic; they are genuinely alive, and the communities inside them are almost identical to the earliest forms of complex life that appeared on Earth over 3,000 million years ago. Thrombolites and their closely related counterparts, stromatolites, are the organisms responsible for producing the oxygen in Earth’s early atmosphere. The Lake Clifton reef is the largest thrombolite formation in the Southern Hemisphere. A purpose-built boardwalk extends from the car park over the shallow lake margins and provides close viewing of the structures without any disturbance to the reef itself. Entry is free. This guide covers how to get to the site, what you will see on the boardwalk, the biology and geology behind the structures, and the strict rules that protect them.

Location and Directions

Address

Lake Clifton Thrombolites, Old Coast Road, Lake Clifton, Western Australia 6215. The site lies within Yalgorup National Park, managed by the Department of Biodiversity, Conservation and Attractions.

Directions

From Perth, take the Kwinana Freeway south and continue onto the Old Coast Road at Mandurah. Drive south along the Old Coast Road for approximately 40 kilometres through Herron and Myalup until you reach the signed turnoff for Lake Clifton on the western side of the road. Turn right (west) at the Mount John Road intersection and continue for approximately five minutes to the car park at the boardwalk. The total drive from Perth is approximately 90 kilometres and takes around one hour under normal conditions. The road is fully sealed throughout and accessible by standard two-wheel drive vehicles. There is a sealed car park with space for passenger vehicles and small campervans. No entry fee is charged at the gate. Toilet facilities are available at the car park.

What Fossils You’ll Find

The thrombolites at Lake Clifton are not fossils in the conventional sense; they are living organisms and are accurately described as living analogues of ancient life. The cyanobacterial communities inside each structure trap and bind sediment grains and precipitate calcium carbonate, slowly building the rounded, clotted mass that characterises the thrombolite form. Individual structures at Lake Clifton are up to two thousand years old based on radiocarbon dating. Because the process producing them today is the same process that produced some of Earth’s oldest fossils, they provide a direct visual and biological connection to the Archaean and Proterozoic eons, more than three billion years of Earth history.

The structures are visible from the boardwalk as irregular, lumpy grey-brown mounds rising from the shallow lake margin, typically between 20 and 50 centimetres in height. At lower water levels or in clearer conditions you can see the biofilm coating the surface of active structures. The reef community supports around 3,000 structures per square metre at peak density. You are not permitted to touch, collect, or disturb the thrombolites in any way. The boardwalk positions you directly above and beside the outer reef edge, giving excellent views.

Geologic History

The Ancient Environment

Lake Clifton is one of a chain of ten coastal lakes within Yalgorup National Park, separated from the Indian Ocean by a narrow coastal limestone ridge called the Spearwood Dune system. The lake is brackish rather than fully marine or fully fresh, with salinity influenced by groundwater upwellings rich in calcium carbonate that flow up from the underlying limestone aquifer. This upwelling of calcium-saturated water is the key trigger for thrombolite growth: as the cyanobacteria carry out photosynthesis, they raise the pH of the surrounding water, causing calcium carbonate to precipitate and cement the sediment grains trapped within the biofilm. The result, accumulated over centuries, is the solid reef structure visible today.

The Yalgorup Lakes formed during the Holocene epoch as the sea level stabilised after the last glacial maximum approximately 8,000 to 10,000 years ago. The dune ridge that formed along the coast isolated a series of low-lying depressions that became the lake chain. Thrombolite growth at Lake Clifton began when the groundwater chemistry and lake conditions aligned to support cyanobacterial communities, and the reef has been growing continuously since. The broader geological context connects the site to the Proterozoic: cyanobacteria first appeared approximately 3,500 million years ago and were responsible for the Great Oxidation Event around 2,400 million years ago, which transformed Earth’s atmosphere from anoxic to oxygen-bearing and made complex animal life eventually possible.

How Lake Clifton Became a Fossil Viewing Site

Yalgorup National Park was gazetted in 1979, covering 11,545 hectares that include the full ten-lake chain and surrounding bushland. The thrombolites were recognised as the park’s most significant natural feature and the boardwalk was subsequently constructed to allow public access without disturbing the reef. The site is listed as a Ramsar wetland of international significance under the Ramsar Convention on Wetlands, recognising its ecological importance as habitat for migratory shorebirds as well as the thrombolites. The Pinjarup Noongar people are the traditional custodians of this country and have maintained cultural connections to the lake system for thousands of years.

Visiting Rules and Regulations

Is Fossil Collecting Allowed?

No collecting of any kind is permitted. The thrombolites are living organisms and are fully protected under the Biodiversity Conservation Act 2016 (WA). Removing, touching, or disturbing them in any way is illegal and can result in significant fines. The site is also protected under the Environment Protection and Biodiversity Conservation Act 1999 (Cth) as a Ramsar wetland. Visitors must remain on the boardwalk at all times. Photography from the boardwalk is welcome and encouraged. Swimming in the lake is not permitted.

Recommended Equipment

No specialist equipment is required. Binoculars are useful for viewing the reef from the further sections of the boardwalk. Sunscreen and a hat are recommended as the boardwalk is exposed. Bring water, particularly in summer. Camera equipment with a macro or close-up capability will produce the best images of the surface detail of the thrombolites from the boardwalk railing. The walk from the car park to the end of the boardwalk and back is approximately 800 metres on a flat, sealed surface and is suitable for prams and wheelchairs.

Safety

The site presents no significant hazards for the average visitor. The boardwalk is well-maintained and has handrails. During hot weather, the exposed boardwalk offers no shade, so visit in the morning during summer months. The lake margin is shallow but the bottom is uneven and there is no lifesaving provision; do not enter the water. The surrounding national park is habitat for dugites and tiger snakes; stay on marked paths outside the boardwalk area and wear closed-toe shoes.

Sources

• https://www.dbca.wa.gov.au/parks/yalgorup-national-park
• https://www.ramsar.org/wetland/australia
• https://en.wikipedia.org/wiki/Lake_Clifton
• https://en.wikipedia.org/wiki/Thrombolite
• https://en.wikipedia.org/wiki/Yalgorup_National_Park
• https://en.wikipedia.org/wiki/Cyanobacteria

New to fossil hunting? Start here! Beginner's Guide to Fossil Hunting!

Have questions? Check out our Frequently Asked Questions.