Tag Archives: gorges

Karajini Part II

Friday 27th  to Sunday 29th September 2013

A long drive today – more than 400 miles. A lot of it was along dirt roads and, as we got near Tom Price, along roads being used by heavy mine construction equipment.

At Tom Price we refuelled, bought food and wine and then headed for Karijini Eco Camp. There we got the same site as we had last time which felt like coming home -almost!

HERE is our route from Exmouth to Karijini. View with Google Earth. Also tomorrows route and pictures.

Part of our route from beyond Exmouth to the Eco-camp at Karijini

Saturday 28th

Today we decided to revisit Knox Gorge but to go downstream when we got there, instead of upstream as we had done last time.

But first we went to the lookout over Joffre Gorge.

Joffre Gorge
The Joffre Gorge Amphitheatre from the lookout. We swam there on our previous visit.

And if we look the other way – – –

Joffre Gorge
Looking downstream – the view from the Joffre Gorge lookout

HERE is the route and pictures of today’s trip. Also the route we took yesterday.

Then we continued our drive to Knox Gorge and descended the steep slope to the stream.

Knox Gorge
Chris descending the scree into Knox Gorge. We headed left – downstream when we got to the bottom.

It was fairly easy walking and we were able to wave to people on the lookout far above us.

Knox Gorge
In Knox Gorge. Note the people in the lookout (top left)

After a bit of easy scrambling we got to the end of the tourist route and contemplated the serious stuff.

Knox Gorge
The debouchment of Knox Gorge into Red Gorge. This carries part of the Fortescue River on its way to Wittenoom, Millstream-Chichester and the sea.

The man in the photo above runs trips into the difficult parts of the gorge. He supplies ropes, harnesses and hardware for descending the steep places. You have to supply a certain level of fitness and several hundred dollars.

While we were there he tried to persuade a couple of young guys to book him for the next day. He glanced at us and passed by with a smile.

Knox Gorge
Just before you get to the end of the easy bit you pass this lovely pool which is great for cooling off. We met a couple of Italian guys who were having a break from working at Karratha.

On our way back up the gorge we took time to look at the rocks. In many places they look like a construction of Roman tiles.

Knox Gorge
The Brockman Iron Formation looking like stacked Roman tiles.

We were able to see the lookout from a different direction.

Knox Gorge
The lookout from inside Knox Gorge

When we got to the exit of the gorge we decided to continue upstream to the swimming hole we discovered last time we were here.

Knox Gorge
Knox Gorge swimming hole
Knox Gorge
Chris at the swimming hole. I presume a waterfall comes down here in the wet.

It is a lovely spot and we stayed here for a couple of hours. Two couples arrived, swam, moved on and came back. The confirmed that this is the best bit!

Knox Gorge
View from the swimming hole, Knox Gorge.

Eventually we moved back to camp, caught up with our emails and bank account at reception, then had a nice supper at the reception.

To end what had been a very good day, a playful breeze caught a contact lens as I took it out and it disappeared. If you find it (Site 90 at the Eco camp) let me know! Thankfully I had my spare so all was not lost!

Sunday 29th

By Western Australian standards today’s trip was a short jaunt – only 112 miles! It was to Hamersley Gorge which is in the north west corner of Karijini National Park, but you have to go out of the park to get there.

HERE is today’s route and photos. Open in Google Earth.

Hamersley Gorge is impressive. there is a new approach road, parking, toilets and a lookout. Geologically it is impressive with some rather impressive folding and a very good demonstration of competent and incompetent beds. But more of this excitement anon!

Hamersley Gorge
Hamersley Gorge from the lookout. For scale note the people in the bottom of the gorge.

The upper walls of the gorge are folded and the thin beds show this very well. Note the whitish rock near the top of the gorge. These are thought to have had the iron removed from them by the action of humic acid produced when the local vegetation was steamy jungle! The iron was deposited in the colourful rocks below.

Hamersley Gorge
Folded beds in Hamersley Gorge.

But the lower beds are not folded – they are dipping but, if they are folded, it is on a much grander scale than can be seen here.

Hamersley Gorge
Folded upper beds resting on unfolded lower beds. Note the white rocks at the top and the colourful ones below.
Hamersley Gorge
Another view of the incompetent upper beds resting on the competent lower beds.


One speculates that when the area came under sideways pressure the weaker beds crumpled while the stronger ones did not – the difference between competent and incompetent beds. So the incompetent beds folded and therefore became shorter; the competent ones did not fold and retained their length. So there must be a slide between the two – a fault parallel to the strata.

The gorge gives several swimming places, separated into pools.

Hamersley Gorge
Hamersley Gorge
Hamersley Gorge
Another pool at Hamersley Gorge

We enjoyed our time at the gorge but soon we drove back to our camp. The next day we would be on our way to Marble Bar.

Hamersley Gorge
Chris swimming a Hamersley Gorge.


Saturday 21st to Thursday 26th September 2013

This was our fastest start – up at 6:30 and on the road at 8!

We first went to the Burrup Peninsula which is, nowadays, an awkward mix of ultra modern oil and gas facilities (pipelines from offshore fields come ashore here), and timeless aboriginal art. We, of course, were after the art but were rather disappointed. Perhaps we were at the wrong place, or did not venture far enough, but what we saw was not as good as what we saw near Newman. I don’t have any decent photos so will have to leave you with a gas flare!

Gas Flare
Gas flare seen fro the Aboriginal art area on the Burrup Peninsula

HERE is a link to our route and photos taken between Dampier and Exmouth.

Part of our route from Dampier to Exmouth

The route was long and tedious – lots and lots of not very much.

Part of our route from Dampier to the Exmouth area

It did become more interesting as we drove up North West Cape along Exmouth Gulf. There are some expensive looking properties with boat anchorages.


Ningaloo Saturday
Detail of our route in the Exmouth Peninsula

When we got to Exmouth we stopped at the Visitor Centre and booked a bungalow at the Lighthouse Caravan Park seventeen km beyond the town – we fancied a bit of luxury and wanted to be assured of our bed before driving onwards.

We were told that accommodation in the Cape Range National Park, if you have not booked in advance, is assigned on a first come, first served basis at the camp entrance, when the ranger comes on duty at 9 in the morning.

Then into town to get some supplies. At the Caravan Park we signed in and settled into our nice bungalow.

Sunday 22nd September

We got to the Ranger station at 8:30 and joined the queue. 45 minutes later we got to the front of the queue and found that the only camp sites available were on the other side of Yardie Creek. This is a long way south and a very long way from Exmouth and possibilities of resupply. So we decided not to go there.

We decided that we would stay at the Yardie Homestead Caravan Park. This is nowhere near Yardie Creek! In fact it is north of the park, on the road to Exmouth. Because I was feeling a bit under the weather and my back was complaining about too much activity, we decided not to camp but to indulge ourselves with a chalet. And we decided to stay for five nights.

After lunch we headed north, had a swim and went up to the lighthouse which gives its name to last nights accommodation. Then back home for a barbecue.

And the temporary filling I got in Port Hedland proved all too temporary! It came out – I will get it replaced when I get back to the UK.

HERE is a link to today’s route and pictures. This includes tomorrows activities.

Monday 23rd September

This was rather a lazy day. Taking advantage of the availability of a pay phone and telephone card at the camp site, we arranged where we would stay on our way back to Perth. Shark Bay was on our list so we arranged four nights at a place near there, also a place on the way – it was  450 miles to Shark Bay!

Then we hired snorkel, masks and flippers from the camp site and headed off to the Lakeside snorkelling area in the National Park.

Lakeside Snorkel Area
The Lakeside Snorkel Area. the white at the skyline is the edge of the reef. The back reef runs from the waters edge to the reef. The fore reef is the slope beyond the reef down to the deep sea floor. It is covered in broken coral.

But it was very disappointing. There was a strong current from the south west and this stirred up a lot of sand, making the water very murky and visibility poor. Also the current meant that you had to paddle like fury to stay in one place.

We stayed in long enough to see that there was a lot of coral and lots of fishes but we were soon back on shore.

Lakeside Snorkel Area
Chris suffering from being unable to snorkel at Lakeside Snorkel Area

We tried again after lunch but conditions were even worse. So we packed up and headed south to look at Turquoise Beach and Mandu Mandu Gorge. We found lots of coral fossils in the gorge – the formation includes Middle Miocene coral reefs, mirroring the modern ones offshore.

HERE is a link to today’s route and pictures. This includes yesterdays activities.

Tuesday 24th September

Tuesday morning was a very lazy time, hanging about the chalet, watching the emus walking past. After lunch we drove south of Exmouth and headed for the hills.

There are a couple of tracks which lead into the Cape range. One goes along a valley – Shothole Canyon Road – and the other goes along a ridge – Charles Knife Road. Both roads were made when the area was being explored for oil deposits.

Shotover Gorge
Our truck parked at the end of the Shothole Canyon Road

Shothole Canyon gets its name from the shallow holes drilled for explosives to aid the seismic exploration of the area. Strangely enough someone found another reason to visit the canyon. See HERE.

Charles Knife Road goes up to the top of the Cape Range to an old wellhead where an oil exploration well was drilled. Parts of the road go along knife edged ridges but that is not the reason for the name. Charles Knife worked for the oil company and laid out the line of the road.

Charles Knife Road
View toward the Indian Ocean from the Charles Knife Road

After our tour of the inland bits of the Cape Range we returned to Exmouth and bought our supper from a local fish merchant – there is a lot of fishing in the area.

HERE is a link to today’s route and pictures. This includes tomorrows short excursion.

Wednesday 25th September

This was a remarkably lazy day! Most of it was spent round the Caravan Park. Before lunch we went to a nearby beach to see if we could see turtles – we couldn’t so we sunbathed.

Chris on the beach
Chris on the beach

Late afternoon we went back to this mornings beach and watched the local windsurfers. Then walked south to something odd we could see in the distance.

Turtles mating on the beach
Turtles mating on the beach. Romance plays an unimportant part in the process.

It turned out to be turtles mating – but we originally thought that the big one was dead! The owner of the caravan site told us what was really going on.  The female has a gash on the back of her neck which you can see in the photo HERE.

HERE is a link to today’s route and pictures. Includes yesterdays route and photos.

Thursday 26th September

After breakfast we decided that we were not beach people and that we would not go to Shark Bay. We much preferred the inland parts of Western Australia. You might conjecture this by the number of photos I took on the coast compared to inland. So we phoned and cancelled our Shark Bay booking.

For our last day on the coast we decided to give snorkelling one last chance and hired what we needed and headed to South Mandu Beach.

And found that the sea was too rough to snorkel! So carried on south to look at Yardie Creek. It does not reach the sea but the pool extends up the gorge. We resisted taking the boat trip up the gorge.

Yardie Creek
Looking inland up Yardie Creek

After lunch (at the Caravan Park) we tried our snorkels at Oyster Stacks but again the sea was too rough, but we had better luck at Turquoise Beach. The water was turbid but at least we got the snorkels wet.

At Turquoise Beach
Corulla eating grass seeds at Turquoise Beach
At Turquoise Beach
Golden sand, turquoise sea, blue sky – another boring Western Australia beach!

HERE is a link to today’s route and pictures.

Purnululu or “The Bungle Bungles” – The North

 Wednesday 28th August 2013

We spent two days in the Bungle Bungles or Purnululu as it is known to the locals. The first day we concentrated on the northern part of the park with a late afternoon drive to look at the southern bit.

Like all Western Australian parks it is theoretically completely open, but in reality you are directed to restricted portions. These bits, however, are (I think) the best bits.

The southern portion is where you find the world famous stripy domes – the northern part is slot canyons.

The Geology of the Bungles is Devonian sandstone, as you can see in the following map.

Bungle geol 1
Geology of the Bungle Bungle area

The route we took on this day can be seen on this extract from the geological map.

Bungle geol28
Route taken and places visited on this day

You can see that there is a meteorite impact structure in the centre of the Bungle Bungles. Seeing it on this map was the first that I became aware of it! I did not notice any evidence for it on our visit to the Bungles.  You can read a bit more about it HERE. It must be younger than the Devonian – probably considerably younger as it has been much eroded.

But back to the slot canyons. We drove north to the car park, looked at the informative signs and decided on our plan. The first we went in was Mini Palms Gorge, named after the Livistona palms which are found in the gorge.

The Mini Palms Trail
Livistona Palms on the Mini Palms trail

At first the gorge is fairly open but the fallen rocks can make progress a bit of a squeeze. As you can see the rocks are mainly coarse conglomerate

The Mini Palms Trail
Chris making her way along the Mini Palms Trail

At the end of the gorge there is a viewing platform from which the amphitheatre can be seen.

The Mini Palms Trail
The amphitheatre at the end of Mini Palms Gorge

Coming down from the top of the gorge is a long cascade of ferns.

The Mini Palms Trail
Ferns cascading from the rim of the gorge

We then drove a little further north and walked into Echidna Gorge. I understand that echidnas are anteaters and likely to be found on the plains – not in the confines of a gorge. And once in the gorge you certainly are confined!

Echidna chasm
Entering Echidna Gorge, where it is still wide enough to have vegetation

As you go further in the walls become closer together and vegetation disappears. When the stream which cuts the gorge is flowing I do not think this would be a place to be. The gorge follows joints which do not appear to be faults. Presumably they formed when the rock became less pressurised as erosion brought it closer to the earth’s surface – remember the impact structure of which we only see the deeper parts.

Echidna chasm
Following a stream eroded joint- I think vertical erosion is stronger than horizontal here!
Echidna chasm
One feels rather small

The chasm gets narrower.

Echidna chasm
Chris in the chasm. I wonder how high the water gets in a thunderstorm?

Because the gorge is so narrow sunlight is not able to flood it – there are always walls in shadow and some in light.

Echidna chasm
Light and shade in the gorge

After a unique walk, taking us into one of the strangest places we had ever been, we turned and walked out.

Echidna chasm
Chris walking out of Echidna Gorge

As we returned to the car park we met a bus load of people making their way into the gorge. Some looked super-fit and others a lot less fit. And a group leader looking worried. It must be very difficult to keep all happy in a situation like that, especially when you consider the cost of these tours.

We lunched at our camp and then headed south. I will talk about that in the next post.

HERE is today’s route and photos. Open with Google Earth.

Karijini – Part 1

 Friday 16th August 2013

John and Julie were to go back to Perth this morning but first we had to repack the trucks so that we had all that we needed fo the next couple of months. and also know how to use it! So first of all some intensive tent pitching practice – up to now the tent had stayed in its bag, but we would need it if we camped in National Parks. Then there was the task of fitting everything we thought we needed into our truck. We thought a second spare wheel was a very good idea but it took up a great deal of space! But eventually everything was sorted out and we went our separate ways. It was about 1400 km for J & J to get to Perth and they did it with two days driving. Chris and I had a mere 80 km to drive. We called in at the park Visitor Centre and enquired about the Karijini Eco Retreat and confirmed that although it was best known for its luxury camping it did have a normal camp site. So of we drove the  35 km and booked in at what was a very nice place to stay.

Karajini geol map
Geological Map of Karijini, with our route on Friday 16th August 2013. Clicking on the map above takes you to its page on Flickr. Click on the three dots on the bottom right and select View all sizes. Select the Original and you will get a very large copy of the map on which you can examine our route and the geology of the park.

We set up our tent in our designated site and set off for Weano Gorge.

Camp Site
Our camp at Karijini Eco Resort

Weano Gorge, at least in the part we visited, is not very deep but it was a challenge for us for we did not realise that it was normal to wade to get along the gorge! So we found our visit a bit restricted, but still spectacular.

Weano Gorge
We did not realise that you were expected to wade through the water! But we could still see the red rocks, blue sky and green gum trees.

But even if one did not go wading to see nice scenery. Weano Gorge was particularly good for reflections of the red cliffs in the water.

Weano Gorge
Red cliffs reflected in the blue water.

And some of the cliffs were very red!

Weano Gorge
Red cliffs in Weano Gorge.

As the sun went lower the colours grew more intense.

Weano Gorge
The reflections of the cliffs became more intense as the sun got lower.

And the white gum trees stood out against the red of the cliffs.

Oxer Lookout
White gum tree against a red cliff.

Then it was back to the camp site to cook our supper. And discovered that we could do with some lighting which was compatible with cooking. John had gone off with his head torch and we only had hand held torches. We each could have done with a third hand! Also as it gets dark before 7 PM and lighting is difficult, there is a tendency to go to bed quite early and to get up with the dawn. Oftimes we would be asleep by 9 and up just after 5. Very different from life at home!

Saturday 17th August 2013

Today we did two gorges, Hancock in the morning and Joffre in the late afternoon. Hancock is close to Weano which we did yesterday and Joffre is within walking distance of our camp. The map below shows where we went and also that all the rocks we saw were Brockman Iron formation

Karajini geol map2
Our route and places visited on Saturday 17th August 2013

Before descending into Hancock gorge we went to the Oxer lookout. This is near the place where four gorges meet. Weano, Hancock and Joffre combine to form Red Gorge and a little downstream, Knox Gorge joins.

Oxer Lookout
The view from Oxer Lookout. We are perched above Hancock Gorge with Kermit’s Pool somewhere below us and behind us on the right. In front is the southern wall of Red Gorge with Joffre Gorge coming in on the right (where the light green water is). Weano Gorge enters opposite. Knox Gorge debouches into Red Gorge one kilometre further on, from the south. This photo has had to be digitally manipulated to lighten the shadows and darken the highlights – this needs to be done for many of the photos of Karijini Gorges.

After the lookout we started down into Hancock Gorge. At first this is just a steep path past red cliffs.

Hancock Gorge
The path into Hancock Gorge.

But then you come to a steel ladder which takes you down a small cliff and you are on the bottom of the gorge.

Hancock Gorge
Chris half way down the ladder into Hancock Gorge.

There is water in the bottom of Hancock Gorge. The stream is barely flowing but the streams course is so rugged that there are pools all along the gorge.

Hancock Gorge
Pool in Hancock Gorge. The blue marker on the right indicates that this is a grade 4 or 5 trail.

But as you go downstream the trail becomes a little more tricky and your scrambling skills are tested.

Hancock Gorge
Chris testing her scrambling skills.

The gorge becomes more constricted and the way more difficult.

Hancock Gorge
The Hancock Gorge trail. Here its straightness indicates that the stream is controlled by jointing.

And then you come to Kermit’s Pool which is where the tired traveller can refresh with a bracing dip.

Hancock Gorge
Kermit’s Pool. The water is very cold! The sun seldom shines down here.

And just beyond the pool you come to signs telling you to go no further. The category of the trail changes from 4 or 5 to 6 and 7 and climbing aids and abseiling skills are required beyond this point. If you pay $A245 each you can go on tours from the Eco Resort with a climber who has the requisite gear for getting into the deeper gorges. He also supplements his income by rescuing people who get stuck in the gorges.

Hancock Gorge
Chris at our furthest point in Hancock Gorge.

So we turned back and headed out, but not before one last backward glance.

Hancock Gorge
Our last look down Hancock Gorge

On our way out we paused to take some photos, Chris put down her camera and forgot to pick it up again! We never saw it again. I passed my spare camera on to her. After lunch back at the camp we rested and then set off to walk to Joffre Gorge. It was then that we discovered the loss of the camera, so our departure was rather delayed as we looked everywhere for it. it is an easy walk to Joffre Gorge, past the rather nice permanent tents of the Eco Camp. You can get into the higher levels of the Gorge easily but getting into the depths is rather more tricky.

Joffre Gorge
Joffre Gorge in the early evening sun.

The low light of the setting sun lit up the higher parts of the gorge and these could be seen reflected in the water in the gorge bottom.

Joffre Gorge
Evening light on the high gorge walls reflected in the pool in the depths of the gorge.

The moon was up and the sun was going down so we headed back to camp, determined to revisit Joffre Gorge on the morrow.

Joffre Gorge
Moon over the Joffre Gorge Lookout.

Sunday 18th August 2013

This was a relatively restful day. We walked to the Reception at the Eco Resort where we plugged in various electric devices for recharging. Only $A5 per item!!! And discovered that you could purchase internet time at $A5 per half hour. We thought that might be useful later. Then we continued to Joffre Gorge and walked as far as we could downstream, which was not very far. There we met a young lady who was enjoying her day off from working at the Eco Resort. She told us that what we could see before us was the “Olympic Swimming Pool”, it was 300m long and very cold. And you could only get out at the far end with an expert climber – rather like the far end of Hancock Gorge yesterday. apparently when it gets warmer the best way of getting along the pool is to “tube it” – get an inner tube from a tyre, sit in it and paddle along. Also have a smaller tube to carry the beers.

Joffre Gorge
The “Olympic Swimming Pool” in Joffre Gorge.

The map below shows how Joffre Gorge leads down to Red Gorge and where we were yesterday. Here we were about 4 km from our exploits of yesterday.

Karajini geol map3
Our route to Joffre Gorge on Sunday 18th August 2013

So turning round we headed upstream. the sun behind us made the rocks glow.

Joffre Gorge
In Joffre Gorge.

We came to a narrow section where we had to splash through the stream but saw that it widened out beyond.

Joffre Gorge
The entrance to the amphitheatre of the Joffre Falls

The wide area was almost circular with vertical walls and with a large pool in the bottom. This was where the Joffre Falls entered Joffre Gorge.

Joffre Gorge
The Joffre Falls. I suspect they are magnificent in the Wet. They are pretty good in the Dry.

The combination of warm sunshine and fairly clean water led to the inevitable – Chris went for a swim!

Joffre Gorge
Chris resting after a swim at Joffre Falls.

After a respectable time at the pool we headed back to reception, picked up our charged items and made a booking for dinner in the resort restaurant. We rested then went back to reception to catch up with emails and other necessities of modern life – mainly moving money to keep up with our spending! Our meal was pretty good – sophistication in the bush.

Monday 19th August 2013

The map below shows what we did today. We drove to Joffre Falls Lookout and then to Knox Gorge. The Lookout is not very far from the camp but it is on the other side of the gorge so a drive of about 5 miles is needed to get there. A further 2.5 miles takes you to the Knox Gorge Lookout.

Karajini geol map4
Route taken to Knox Gorge on Monday 19th August 2013

The Lookout gives a different view of the falls and the amphitheatre.

Joffre Lookout
Joffre Falls from the Lookout

It is a steep walk into Knox Gorge and the signs at the bottom indicate that you should walk downstream. But upstream looked pretty good and that is the way we went.

Knox Gorge
Looking upstream at the base of the descent into Knox Gorge.

The rocks are Brockman Iron Formation and look as if they had been cast from molten iron! But of course they are sediments laid down 2.5 billion years ago.

Knox Gorge
Brockman Iron Formation, Knox Gorge.

A few hundred yards upstream we came to a rather nice swimming hole which we much enjoyed.

Knox Gorge
Swimming Hole in Knox Gorge.

After an hour or two we went back to camp and got ready to leave Karijini. As you can probably tell we enjoyed our time in the Park and we came back almost 6 weeks later.

Our First Few Days – Hickman Crater to Karijini

On rising we set off back towards Newman so that Chris and I could get enough provisions for our first period on our own. But driving along the railway line we saw an ore train and took the opportunity to photograph it.

Newman to Port Hedland Railway
Ore train from Newman to Port Hedland

Typically these trains are 2.63km long, have 248 wagons each carrying 126 tonnes of ore. That adds up to 31,000 tons per train.

Newman to Port Hedland Railway
Ore Train

Usually there are eight trains per day, so a quarter million tonnes are transported every day. It takes 8 hours to cover the 426km to Port Hedland. Later, after our time in Karijini, we drove along the very similar Mount Tom Price to Dampier Railway, operated by RTZ (Rio Tinto Zinc). Iron ore is BIG in Western Australia.

We did our shopping and set off for Karijini along the Great Northern Highway. As we approached Karijini we looked out for potential camp sites and spotted a candidate a few miles from the camp boundary. We checked it out by having lunch there and gave it a somewhat reluctant thumbs up – it was not far from the road.

View of the Hamersley Ranges
View of the Hamersley Ranges from our lunch spot and camp site. Note the flat lying Banded Iron Formations – BIFs.

After lunch we drove into the park, had a walk round the Visitors Centre, then headed for Dales Gorge. We looked at the Camp Site which, after our experience of wild camping, seemed very crowded! Then had a walk to Dales Gorge and saw our first Karijini gorge. Almost all the rocks we saw were the Brockman Iron Formation, part of the Hamersley Group. They are about 2.5 billion years old and look remarkably well preserved for their great age.

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Dales Gorge

Walking along the top of the gorge we soon came to the Fortescue Falls which were actually flowing but not as much as they would in the wet season.

Dales Gorge
Dales Gorge and the Fortescue Falls.

From the top of the falls one can look along the gorge.

Dales Gorge
Dales Gorge from the top of the Fortescue Falls. This is a composite of three photos as the contrast between light and shade was too great to be captured in one exposure.

The rocks of the gorge look very straight forward, flat-lying sediments until you look at them more closely. Then they become rather more complex. An article in Wikipedia  says:-

The conventional concept is that the banded iron layers were formed in sea water as the result of oxygen being released by photosynthetic cyanobacteria, combining with dissolved iron in Earth’s oceans to form insoluble iron oxides, which precipitated out, forming a thin layer on the substrate, which may have been anoxic mud (forming shale and chert). Each band is similar to a varve, to the extent that the banding is assumed to result from cyclic variations in available oxygen.

It is unclear whether these banded ironstone formations were seasonal, followed some feedback oscillation in the ocean’s complex system or followed some other cycle.

It is assumed that initially the Earth started out with vast amounts of iron and nickel dissolved in the world’s acidic seas. Eventually, as photosynthetic organisms generated oxygen, the available iron in the Earth’s oceans was precipitated out as iron oxides.

At a suspected tipping point where the oceans became permanently oxygenated, small variations in oxygen production produced pulses of free oxygen in the surface waters, alternating with pulses of iron oxide deposition.

So wee beasties, polluting their own environment – oxygen wasn’t good for them – caused the composition of the sea and the atmosphere to change and rust to deposit on the beds of the oceans. You would not get planning permission for it nowadays! However it enables us to live the life we live – what would we do without iron?

Dales Gorge
Brockman Iron Formation at Fortescue Falls. This photo is now used to illustrate “Banded iron formation” in Wikipedia!


Dales Gorge
More Brockman Iron Formation at Fortescue Falls


Dales Gorge

Roots of a fig tree near Fern Pool

Walking upstream from the falls we came to Fern Pool which is a lovely pool for swimming – I enjoyed it so much that I forgot to take a photo! But here is a photo of people swimming in the pool below the Fortescue Falls.

Dales Gorge
Swimming in the pool below the Fortescue Falls

By this time it was getting late so we headed back to our lunch spot and set up our last camp together. To morrow John and Julie would be heading back to Perth while Chris and I would be on our own!

Roy Hill geol
Geological Map of today’s travels.

HERE is today’s route and photos. Open with Google Earth.