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The Stromatolites of Lake Thetis

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by ElizaDoLots (subscribe)
"The cure for boredom is curiosity. There is no cure for curiosity" - Dorothy Parker
Published August 20th 2018
Living fossils which are legends in their own lifetime
Two and a half hours up the coast from Perth lies the Pinnacles Desert, sparsely-vegetated home to thousands of limestone spires and stumps. A natural phenomenon of unknown age and origin, the Pinnacles attract around a quarter of a million visitors each year. Many of these same visitors are oblivious to the fact that another ancient wonder, equally worthy of their admiration, lies just a few kilometres to the north.

The Stromatolites of Lake Thetis
Lake Thetis, Cervantes

Lake Thetis, on the outskirts of Cervantes, is the site of a colony of marine stromatolites. Rather more is known about the origin of the stumpy stromatolite than the impressive Pinnacles. These rock-like mounds may have the appearance - and all the appeal - of dried cowpats, but don't let this fool you. The stromatolites of Lake Thetis are living fossils, populated by dense communities of microbes, not visible to the human eye. The oldest and largest living fossil known to man, the stromatolite is evidence of the earliest life on earth.

Lake Thetis, Cervantes
Lake Thetis Loop Trail

Stromatolites are domes and columns formed by cyanobacteria (blue-green algae) and other organisms trapping and binding particles of sediment over an incredibly long period of time. A one-metre stromatolite structure can take up to three thousand years to form. The stromatolites of Lake Thetis have been growing in its saline waters for the past 3,400 years.

Cyanobacteria were around long before any other life-form on earth and have stayed virtually unchanged for billions of years. Modern, living stromatolites are closely related to the oldest known stromatolite fossils, found in the Pilbara, which date back 3.5 billion years.

Lake Thetis, Cervantes
Stromatolites of Lake Thetis, Cervantes

As if their age isn't mind-blowing enough, stromatolites are believed to have had a crucial role in the evolution of life on earth, by contributing oxygen to the earth's atmosphere. When stromatolites first appeared on earth over three billion years ago there was little or no oxygen in the atmosphere. It's thought the photosynthetic cyanobacteria found in stromatolites were responsible for increasing the oxygen content of the earth's atmosphere from less than 1% to around 21%, making it possible for oxygen-breathing animal life to develop.

Lake Thetis, Cervantes
Information board at Lake Thetis

Stromatolites need light to grow so are limited to shallow water where sunlight can penetrate. Until a billion years ago, it would have been possible to find stromatolites on the shores of many lakes and seas around the world. Today, living stromatolites can only be seen in a small number of places, Lake Thetis being one of a handful of accessible sites in Australia.

Lake Thetis, Cervantes
Stromatolites of Lake Thetis, Cervantes

There is a 1.5 kilometre, compacted-gravel walkway all around the lake and also a viewing platform with information boards. The first 300 metres of boardwalk, which passes the best examples of stromatolites in the lake, is universally accessible. The best time of year to visit is in winter when the water level is low, making the stromatolites very visible.

Lake Thetis, Cervantes
Stromatolites of Lake Thetis: tenacious, but not tough

If visiting the Pinnacles is on your bucket list, it's worth adding the lowly stromatolites of Lake Thetis. It's not often you can say you've taken the trip of 42 lifetimes and glimpsed the dawn of life on Earth.
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Why? Because the time machine has yet to be invented
When: Daylight hours advised
Phone: 08 9652 7913
Where: Hansen Bay Road, Cervantes, WA 6511
Cost: Free
Your Comment
Interesting, ElizaDoLots - will definitely have to put that on my bucket list!
by Elaine (score: 3|8670) 1250 days ago
Beautiful lake; it looks so serene.
by Bastion Harrison (score: 4|12626) 1248 days ago
Amazing article Eliza, never knew these even existed!
by micha (score: 0|3) 1250 days ago
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