|Pilbara - Mt Whaleback Mine and Wanna Munna||May 3 - 4 2018|
|BHP Mt Whaleback Mine tours leave the info centre at 09:15.
Be there at 09:00.
So we rose at 05:30 and wended our way out of the crater when there was sufficient light from the sunrise.
|The last pitch down to the level of the plain.
We felt a bit uncertain about our navigation, even something simple like retracing steps can be a nightmare if one wasn't concentrating.
Note to self .... next time driving on tracks that aren't on maps record the gps track!
Seeing our tyre marks from the journey in helped. Basically find way to base of hills then turn left towards Punda.
|Such a green land .......... but a very dry land.|
|We arrived for the tour with about ten minutes to spare.
The Mt Whaleback Mine is the largest open cut iron ore mine in the world.
A nice complement to our tour of the Kiruna underground iron ore mine in Sweden.
This mine is hematite. Kiruna is magnetite.
The average iron content of finished product (fines or lump) is above 60%. Very high grade.
Most of the action is in the distance, at the west end of the mine. Below the water table. This end is being back filled. Surprisingly (to me) anything less than about 60% iron is discarded. And some of the ore has a higher than acceptable sulphur content. So far about 1,000,000,000 tonnes of product has been shipped, since 1967.
|The drill rig, somewhere about centre in the above pic, is
remotely controlled from Perth.
The explosive is ammonium nitrate and diesel. A very controlled blast to fracture the ore rather than send up a big cloud of dust. A couple of times each week as required.
|Fifty haul trucks carrying about 240 tonnes each.
And a water truck with 100,000 litres to keep the dust down.
"Drive this truck around for 3 hours until its empty then fill it up and start again!"
|Pit 39? Also high grade ore, but yellow and sticky. Ochre. A hydrated iron hydroxide rather than iron oxide. Blended with the blue grey ore, lest it clog the bene plant, in fines.|
|The explosive didn't quite do its job. This rock would have become stuck in the primary crusher. The drill hole takes 600-800 kg of explosive.|
|Ore is crushed on site. The "bene" (beneficiation) plant.
The conveyor in the back left is providing finished product for loading - there's a tunnel under the ore pile through which trains travel, moving continuously, for loading.
|After the tour we filled our water tanks at the visitor
centre, filled our fridge from the supermarket, bought some windscreen wiper
blades at the hardware store, a new scientist from the newsagent, filled the
fuel tanks at the fuel station, checked email, put some more air in the
tyres, then headed towards Karijini National Park. North west from Newman.
Mt Newman in front of us.
We are cruising at 80 km/hr. Horribly fast! The road is smooth and wide. We are not used to this.
We stopped at Wanna Munna, about 70 km from Newman, for some more petroglyphs and camping.
|We had a brief look in the small gorge in the early evening
but the sun was in the wrong place for us. At least that's our excuse.
Next morning we were not so tired and spent a couple of hours exploring the rocks and the creek.
We couldn't avoid making comparisons to Pandu. Here it seems the petroglyphs are a bit less distinct. Less obvious to us, we had to work a bit harder to find them.
On the other hand, this is obviously a kangaroo. Its tail hidden in the shadow.
We aren't trying to document the site. Just remind ourselves of what we have seen. And possibly to help settle future discussion about what we saw.
|We think a kangaroo with a person. Unsure of which came first.|
|We found fewer circles than at Pandu.|
|We are not sure if its a penny dropping or not. The bands
across the person and goanna begin to suggest to us that there are outlines,
outlines filled with bands, and coloured in.
I wonder if its a result of how much energy the artist had, or whether its different artists at different times.
|Standing back a bit. We are in a narrow, shallow, gorge.|
|A veritable jumble. Deeply engraved.|
|We are intrigued by depictions of people. We think.|
|This is surely an emu. In outline.|
|We headed downstream. And looked back.
We are in a branch of Weeli Wolli Creek. There are many branches that form and combine on the south side of the Hamersley Range. Its one of a few creeks that flow all the way through to exit the range to the north. And disappear into the sands before reaching the Fortescue River.
There are vehicle tracks marked alongside it. With a small gap in the middle.
|Then couldn't imagine what has 5 pairs of legs.|
|So we went back to looking at people.|
|It must be a dry year. This is the only real pool we found.
As we walked downstream.
There was another, almost dried up, that cattle frequent.
|This caught our attention as it is so much like the "not
black but glassy" rock we saw on the rim of the meteorite crater.
Which probably means that while it may be metamorphosed it wasn't because of the impact.
It may just be polished by rain or wind. To our unpractised eyes it doesn't have the roundedness of river stones.
|There's a 30m stretch of the creek that is crossed by bands
of rock that are similarly shiny. About 1.3km downstream from the
At least the most exposed is shiny, otherwise remnants of mud from pools as they dried hide it.
|There are some beautiful patterns.|
|Its like a series of walls across the creek.
I looked hard to find the boundary between the rock in the floor of the creek and the rock in the sides.
I have no doubt there is one, but I couldn't find it. The bedding planes are continuous between floor and sides. Just that beneath our feet its this polished grey and yellow stuff while the sides are crumbly reddish stuff (to put it in technical language).
|In some places the rock has been broken across the
Reminiscent of sawn through tree trunks but on examination perhaps just the way its been eroded and broken. But it looks like "tree". About 450mm diameter.
When we looked at "the ends" we could imagine rounded, river worn, stones that were part of the sediment.
|We could also see stones looking from "the sides".
Ever more beautiful.
We think we are looking at jasper. We've only ever seen small river worn stones of jasper. This is a big seam.
Rocks and minerals are harder for us to identify than birds. Birds have distinctive shapes and colours while all have feet, wings, and beaks. Rocks and minerals have much more variety. More species .... with different origins and no common ancestor.
But we think "jasper" is a feasible conclusion. Jasper is a form of chert. As is agate. Jasper is silica, with impurities to give it colour and opaqueness. Formed through hydrothermal activity - silica crystallising (micro crystals) from sea water. Agate is transluscent.
We can well imagine our "tree" getting in the way of the process, being in the wrong place and time. There are places in the world where petrified trees appear in jasper, but of course we can't be certain here. We also know that agates form in geodes (nodules or spheres with agate inside), as does jasper. Perhaps that is our stones, though we'd prefer they were more spherical.
It also occurs to us that Marble Bar (the town some long way to the north east of us) actually has a Jasper Bar. When we visit there we will have a reference.
Reasonably consistent with Banded Iron Formations that are most of the Hamersley Range, also crystallised from sea water.
Of course one would have to ask the obvious and inevitable question of how the tree arrived and was petrified. Our understanding of the banded iron formations is they were formed in an era when cyanobacteria were the dominant life form. If there is a petrified tree it must have been petrified at a later date. Many millions of years later.
So far we are moderately comfortable with our mental meanderings. And continue to wonder at the world around us. A wonder that is somehow independent of "how" or "why".
|So back to camp. The sun has moved round a bit to give us a
more clear look at the kangaroo.
Looks like there's a second kangaroo, drawn at the same time, part of the same story.
The rock looks to us almost as if its been drawn on several times.
If someone were to ask should they visit Wanna Munna or Punda we would probably say both. They are sort of "the same but different". Just that one is more accessible than the other.
|Pilbara - Mt Robinson and Mt Meharry||May 5 -8 2018|