Everything you need to know about the Eurypterid and Skolithos trace fossils of Kalbarri National Park, Western Australia.
Kalbarri is undeniably one of the most picturesque towns on the Western Australia coast. With the wide sweeping Murchison River mouth and white coastal cliffs sheltering the town, it is a camping and fishing dream. The incredible red sandstone gorges of Kalbarri National Park are a sight to behold and offer some of the best hike trails in WA (in my humble opinion). And yet the absolute best thing about Kalbarri, is something that very few people even know about!
I am referring to the real stars of the show, the trace fossils. For within the gorges and along those mighty coastal cliffs you will find fossil evidence of the very FIRST life to walk on land! Yes, you read that right. We may not have a full Diplodocus skeleton or the femur of a T-Rex, but we have something far, far more significant.
Before the time these trace fossils were formed, there was no life on land, not even much plant life. It would have been very barren. But for seem reason some adventurous little creatures decided to pop their head out above the waves and see what lay over the crest.
To really give you good idea of why Kalbarri is so important to all of our history, I am going to have to take you back, way back to somewhere between 400 and 500 million years ago…
And if you enjoy the geology of WA posts, check out these ones below 🙂
- Crystal Quest at Sugarloaf Rock
- Black Point – the Bunbury Basalt on the south coast
- Living Fossils at Lake Clifton, Mandurah
Kalbarri in the Silurian
If you looked a map of WA 500 million years ago there is a very good chance that you would not recognise where we are. At this time we were still part of the giant supercontinent Gondwana. Much of what we see today in WA had not even been formed; only the ancient cratons (the first building blocks of landmasses) existed; the Yilgarn and Pilbarra cratons of WA, plus the first pieces of present day Antarctica to the south and India to the west.
Around this time a shallow sea was forming along what is now the west coast of WA (when WA and India were still conjoined and the Indian Ocean did not yet exist). This seaway extended in a narrow band up to the northwest. The area would have been covered in wide sand tidal flats. With no vegetation to bind and support river banks the channels would have migrated back and forth across these sandy plains. We can see evidence of this in the crossbedding seen at some locations in the gorges.
The land would not have been green and lush as we see it today, but was stark and lifeless. There were no trees and plants, not even grasses. In fact, grasses didn’t evolve until just 55 million years ago – that is after the extinction of the dinosaurs.
The sands that were deposited in this time were subsequently buried by later sediments deposited on top, and in time became solid rock. The rock preserves the sedimentary structures that give geologists an idea of the environment, some we can see today are the crossbedding of moving dunes and ripples, and the filled in river channels. This sandstone in Kalbarri is now called the Tumblagooda Sandstone.
To explore what the earth would have looked like at any point in time you can explore this paleo-map Interactive Earth.
The first plants on land
The very first greenery on dry land appeared around 470 million years ago in a time known as the Silurian. These would have been simple mosses that did not have stems to support vertical growth, and would have clung close to the shore. In short, it would not have been very inviting with no shade from the wind and sun, nothing to eat and little shelter. Perhaps this is why it took so long for animal life to colonise land.
Abundant life in the oceans following the Cambrian Explosion
The oceans on the other hand were thriving and abundant with life of all forms. Aquatic life had just gone through the Cambrian Explosion; a period of 12-25 million years of immense evolution and the first emergence of many phyla (families of closely related species) we see today. This occurred around 540 million years ago.
Those first footsteps on dry land
Perhaps due to this sudden (in geological timescales at least) explosion of life in the oceans, or perhaps to avoid predators or find a peaceful spot to procreate, one particular little arthropod decided to go where no one had ever been before; out of the ocean and onto dry land! This is a pretty momentous milestone in the evolution of life on Earth, and believe it or not we can see evidence for this ourselves in Kalbarri National Park! The best bit – we can TOUCH it!!
Eurypterid trace fossils in Kalbarri National Park
The Eurypterids are types of arthropod that actually evolved earlier in the Ordovician (443 to 485 million years ago) as fully marine animals, but sometime, probably in the Silurian (419-443 million years ago), they ventured onto land – and incredibly their FOOTPRINTS have been preserved for us to see today!
There are places in the national park where you can touch these footprints for yourself. At these locations you can put your hand on the footprints and like a bookmark in time, everything before that moment land was barren, and after that moment land blossomed. Everything you can see before you today that is not rock, evolved after that footprint; wood for building, the primitive plants that evolved into the food we eat, the first insects, first flight. And this is the one that blows my mind a bit; there would have been no fire before either, as there was nothing to burn.
This area is so important in fact that this particular species of Eurypterid was named Kalbarria.
The footprint fossils form two parallel lines of pad marks that in places are well defined and in others are more like skid marks. They can be from 1cm to 25 cm apart.
Arthropods – invertebrates with jointed legs and include insects, arachnids (e.g. spiders) , crustaceans (e.g. prawns) and myriapods (e.g. centipede) – you can read more at the Australian Museum website. Invertibrates are animals without a backbone or boney skeleton.
So, what is a Trace Fossil?
A trace fossil is a marking left behind by an organism and it can be footprints, as with the Eurypterids, burrows, trail, boring, etc… The technical name for a trace fossil is Ichnofossil – and the study of trace fossils is called Ichnology. If you want to study another fun type of fossil you could always study coprolites – fossilised poo!
These Ichnofossils are formed when a footprint for example is made on a sediment, then that sediment dries out and hardens before the next layer is deposited on top. That next layer could be the next high tide, a storm surge or a rain storm washing more sediment down a river suddenly.
Where to find trace fossils in Kalbarri National Park
This is the fun part! I can guarantee you that 99% of people who visit Kalbarri National Park miss these trace fossils, and even if people do see them, they don’t know the significance. I have been preaching to my friends about this incredible markings when I hear they are visiting Kalbarri but even they miss them when they get there – so follow these steps and you will be able to find them for yourselves 🙂
One of the features here is famous and recognisable to most Aussies, and the other should be recognisable by most Aussies haha! Natures Window is a natural rock formation through which you can view the stunning gorge and Murchison River below.
The path down from the carpark to Natures Window is paved and an easy walk with plenty of photogenic views. About half way down to Natures Window you pass a gorgeous view to your left with a simple wooden bench. If you sit at this bench and look at your feet, you will see a Eurypterid trace fossil track! Simple as that 🙂
Towards the end of the paved path from the carpark, just as you approach the lookout, look down and you will see another set of traces fossils. The only photo I have of the trace fossils at the Z bend lookout – with my Maddie standing over them – doh! Not particularly helpful, but still cute though 🙂
Four Ways Trail
At the base of the Fourways trail you may find the area known as ‘track central’, a flat surface a couple of metres across that is covered in criss-crossing tracks. Alas, have not explored here myself so I cannot supply a photo or detailed directions.
The Kalbarri Skywalk
Along the route to the new Skywalk there is another example of the trace fossils, this time with a small Kalbarria statue to illustrate the pioneering little critter. Watch this space for more photos.
Ross graham Lookout
On our first explore of Kalbarri National Park back in 2017 the main areas were closed for maintenance so we decided to explore the river around Ross Graham Lookout. After an hour or two of searching, and just before we headed back to the car, I found some trace fossils!! It was quite an exciting find and you can read all about it in what was my first ever blog Family Fossil Hunting in Kalbarri National Park.
The ONE body fossil found
Why all the fuss about trace fossils? Can we not find a fossilised Eurypterid itself? We have only found one and that’s an imprint of the body, giving us an idea of what they looked like. The reason we don’t find body fossils is because the environment that formed this Tumblagooda Sandstone was not very good for preserving organic material. It would have been a high energy environment of flowing and very changing braided rivers, and intertidal coast. This means that any deceased Eurypterids would have been broken up by the water movement, and the highly oxygenated water means decomposition would have occurred relatively fast.
When did the Eurypterids live? And how old are the fossils?
This is a tough one! The nature of the environment in which this Tumblagooda Sandstone was deposited, as mentioned above, was not ideal for preserving body fossils – and these are often how geologists constrain the age of a rock. But here are the age constraints:
The oldest Eurypterids: The earliest dated Eurypterids are known to be from the Lower Ordovician (478-471 million years ago).
The oldest the sandstone could be: radiometric dates of mineralisation in the Northampton Complex which lies beneath the Tumblagooda Sandstone in places has been dated at roughly 434 million years.
The youngest the sandstone could be: The Tumblagooda Sandstone is overlain by a rock unit called the Dirk Hartog Formation and this unit has been estimated to date from the Upper Silurian – meaning the later part of that 419 to 443 million year period.
And so the Eurypterid trace fossils must be between 419 and 434 million years old – give or take 10-20 million years.
But wait, that’s not the only Trace Fossils in Kalbarri National Park!
As if that isn’t enough to keep you busy and excited for days in Kalbarri National Park, you can also head to the coastal section of the national park and wander at the trace fossils there too.
In several places along the coastal walks you will see these funny looking rock cylinders dangling from an overhang or threaded through the layers of the distinctive sandstone. These are Skolithos; vertical burrows made by small creatures in a shallow sea that was later infilled by more sand.
Amazingly, these particular trace fossils are remarkably similar to ones found in Antarctica which if you remember was adjacent to WA at the time these rocks were formed.
In fact, it was similarities between fossils in rocks on now distant continents that first prompted pioneering geologists such as Alfred Wagner to propose the theory of Continental Drift – which evolved into the Plate Tectonic Theory we have today! So these little fossils are pretty special!
And so, now we know why you want to go explore Kalbarri National Park, you need to know the rest:
Where to Camp in Kalbarri
Unfortunately, there are no national park camps in Kalbarri but there are plenty of lovely caravan parks in the town itself, plus Murchison House Station Stay.
- Kalbarri Anchorage Caravan Park – (08) 9937 1181 – website
- Murchison River Caravan Park – (08) 9937 1005 – website
- Kalbarri Red Bluff Tourist Park – (08) 9918 7100 – website
- Kalbarri Tudor Holiday Park – (08) 9937 1077 – website
- Murchison House Station – (08) 9937 1998 – website
If you prefer bush camping you can explore Lucky Bay Campground to the south.
Hikes in Kalbarri National Park
The Hikes of Kalbarri National Park:
- Malleefowl Trail – 1.5km loop – 1 hour – class 3
- Red Bluff to Beach Trail – 700m one way – 20mins – class 3
- Mushroom Rock Trail – 3km loop – 1 hour – class 3
- Pot Alley Beach – 400m return – 2omins – class 3
- Eagle Gorge Beach – 1km return – 35-40mins – class 3
- Bigurda Trail (Eagle Gorge to Natural Bridge) – 8km one way – 3 hours – class 3
- Nature’s Window – 800m return – 30-45mins – class 3
- The Loop Trail – 9km – 3 to 5 hours (this one took me 2 hrs 45 mins – read about it here) – class 4
- Four Ways Trail – 6km return – 2-4 hours – class 4
- Z Bend Lookout – 1.2km return – 1 hour – class 3
- Z Bend River Trail – 2.6km – 2 hours – class 4
- Ross Graham River Trail – 700m return – 30mins (unless you go hunting for fossils like we did 😉 ) – class 3
For great information on the hikes in Kalbarri National Park you can check out the following resources
And I can definitely recommend hiking The Loop Trail – you can read my account of it here
More Kalbarri blogs from Keeping Up With Little Joneses
- Family Fossil Hunting in Kalbarri National Park
- The Coastal Hikes, Kalbarri National Park
- Hiking The Loop Trail, Kalbarri National Park
Other useful links:
- Kalbarri National Park brochure
- Department of Mines, Industry, Regulation and Safety Kalbarri Trace Fossil info
- Geological Guide to the Kalbarri Area by DMIRS (downloadable PDF – free)
I would love to hear what you think of these intriguing fossils – please share in the comments below 🙂