Boy do I feel old. Wait a minute. I’m young compared to the discovery of the Burgess Shale fossil beds in 1909. To the end of the last ice age 11,000 years ago. To the beginning of the ice age 110,000 years ago. To the end of the dinosaurs 65 million years ago. To the beginning of the dinosaurs 230 million years ago. To the life-filled environment at the bottom of the ocean over 500 million years ago and the origin of the Burgess Shale fossils.
I guess I don’t feel so old after all. In fact I feel young again!
The Burgess Shale, located in Yoho National Park within the Canadian Rockies, 210 kilometres (132 miles) west of Calgary, Canada is an absolutely amazing place to catch a glimpse into the very distant past of our living planet.
The Burgess Shale site is one of the most well known and world renowned locations for unique and extraordinary fossils which changed views of how life evolved.
Way back when, in the midst of the Cambrian Explosion, a period when a massive proliferation of animal life on earth transpired, is when this story begins. We’re talking (gulp) 505 million years ago.
Why are Burgess Shale fossils so special?
There are a multitude of Cambrian age fossil discoveries around the world which shed light on what was in existence so long ago. These fossils are almost all exclusively of hard-bodied creatures.
What makes the Burgess Shale so unique is that only 2% of the fossils found here are hard-bodied fossils, with 98% being soft-bodied fossils.
It takes an extremely unique environment to accommodate the preservation of soft bodied creatures for half a billion years. Only a very few locations in the world have these types of soft bodied fossils, and not nearly at the volume as the Burgess Shale.
Life at the bottom of the sea
About 505 million years ago, sea life thrived in an aquatic oasis below an escarpment attached to a large land mass, named Laurentia (later to become North America).
Fossils of about 150 different species of animals, algae, and bacteria have been discovered in this area.
Some examples of the peculiar body designs of the Burgess Shale animals include:
Anomalocaris – The largest of the Cambrian predators in this area (up to 1 metre or 3.3 feet), its head includes two protruding eyes, two elephant trunk-like appendages, and a circular shaped mouth with sharp spines pointing into a square opening.
Leanchoilia – This 4-eyed being with an armored-looking cover, has two appendages, each with 3 whip-like branches. This little guy could easily star in a sci-fi alien movie!
Opabinia – With five protruding eyes, a pincer-tipped garden-hose appendage sticking out from the head, it is arguably the most peculiar looking of the Burgess Shale creatures. Wouldn’t we look different if this was our distant ancestor!
Pikaia – Although not an exciting looking little creature, its claim to fame is to be our very distant ancestor. This fish-like chordate animal is the early beginning of the evolution to vertebrate animals. Do you see any resemblance?
The list of bizarre and fascinating Cambrian shale creatures goes on and on.
How are fossils formed?
Every once in awhile a storm brews; stirring up mud and sediments on the escarpment above. The mud-sediment mix then flows off the underwater cliff to blanket portions of the quiet ocean floor below.
Some ill-fated sea creatures whether digging, crawling, floating or swimming, get quickly covered by the mud. Lucky for us, this mud protects the unlucky animals from scavengers. Also, lack of oxygen slows decay of these expired beings.
This situation repeats itself over and over again for about 200,000 years (will those creatures ever learn)! To put that time frame into perspective, modern humans have been in existence for 200,000 years, and civilization as we know it is a mere 6,000 years old.
As the additional layers of mud and sediments (around 100 metres or 330 feet in total) cover the ocean floor below the cliff, the captured creatures and the sediments compress and fossilization begins!
With the fossilization process underway, Laurentia (with the escarpment tagging along) travels across the globe, finally arriving in the northern hemisphere where North America now resides.
How did the fossils come out of hiding?
The same tectonic forces that move the continent across the globe also raise the escarpment some 2.4 kilometres (1.5 miles) as part of the Rocky Mountain building process.
Erosion over millions of subsequent years eventually exposes the same ocean floor remnants from so long ago, now known as the Burgess Shale.
For a visual (and entertaining) explanation of the creation of the Burgess Shale, check out this video
How can I see the Burgess Shale?
Although there are a few quarry sites along a 60 km span of the Burgess Shale, the most prolific and well known Walcott Quarry is situated on the side of Fossil Ridge (aptly named) at 2,336 metres (7,760 feet) above sea level.
To get there requires a somewhat taxing 11 hour guided round trip hike of 22 kilometres (14 miles) from the Takkakaw Falls parking area, including an 825 metres (2,710 feet) climb. The hike is considered hard due to its length. Oh, but the amazing mountain and lake scenery makes it all worthwhile!
The quarry is available only with guided group hikes. There are two options for guided hikes, which are with Parks Canada or the Burgess Shale Geoscience Foundation.
Where are the Burgess fossils now?
Over the years, a vast number of the fossils in slate have been removed from the Burgess Shale quarries. There is no one Burgess Shale museum. For example, the Geological Survey of Canada (Ottawa) has 10,000 specimens, the Smithsonian Institution (Washington, DC) has 65,000 specimens, but the main prize goes to the Royal Ontario Museum (Toronto) with 150,000 specimens.
A great place to really see what the creatures looked like and the environment they lived in is at the Royal Tyrrell Museum (Drumheller, Alberta) which has an excellent larger-than-life display dedicated to the Burgess Shale (and no 22 kilometre hike required!)
New Burgess fossils are continually being discovered. There are very strict rules about not removing any fossils from the quarries. In 2016 a foreign tourist was caught with a fossil hidden in his backpack and was fined $4000. In other words, look, touch and photograph, but don’t take! Should you see an advertisement that reads, ‘Burgess Shale fossils for sale’ my advice is to steer clear.
What are the most intriguing hikes in your region?