Time to Burn: The Land

I’ve noted in the past that the Australia is a dry land.  The proximate cause of this is the generally northward movement of the Australian Plate over the last 40 million years or so.  This triggered an overall drying out of the continent, especially the interior, far from any sources of wet air.  Geology dominates (again).  You can watch this here.  The flora and fauna adapted to the drying.  The role of fire was likely enhanced when people first arrived, at least 60,000 years ago.  Burning has numerous advantages for the hunter/gather lifestyle.  The flora and fauna certainly readapted to this human impact. 

The role of aridity on the land is not immediately apparent, especially in winter.  It’s green and sometimes rainy in the Perth area.  There’s an ocean nearby, and the Swan River cuts through the city.  Green lawns are abundant, even in Perth’s sandy soil. 

The Pilbara is different.  Whether arriving from the south by plane or vehicle, I’m always confronted with entering a semi desert.  The air is drier.  The sun feels hotter and more intense, nearer to the equator.  Beyond the margins of human modification, the landscape is immediately stark.  No water.  Red-brown earth mixed with loose rock.  Spinifex and termite mounds.  Wattles and mulga.  Rare flowers, often yellow, sometimes red or lavender.  My shoes coat with red dust the moment I step onto the ground.  There is often wind.  If not, there is silence.  Depending on the time of day, birds, lizards, and insects may add motion.  Flies are almost always present. 

I’m fond of this beauty.  The colors are right.  The landscape has an apparent minimalism: a few major components, repeated innumerably.  The land is open; I like seeing such long distances.  I feel this fitting in most arid settings, especially if they have red rocks. 

Back to Australia Fifteen.  We swagged out for two nights west of Paraburdoo, along the southern edge of the Hamersley Basin.  During my visits, this has seemed to be the driest part of the Basin.  I think it suffers from the rain shadow effect of all the mountains to the north.  By the time the summer cyclones that bring the Pilbara most of its rain get here, they have lost much water.  The plants are also a bit different; maybe this reflects the relative lack of moisture. 

We’d found a swag out site in a broad valley north of the road.  As I walked around gathering fire wood and looking for the right place to sleep, I kept thinking, something’s not right here.  I finally realized: there was no ground cover.  No grass, no spinifex, just dirt and broken rock.  The emu bushes near camp were wilted.  They seemed to have stopped growing and had drooped in the middle of flowering.  I kicked at the ground.  It was very dry, very dusty. 

Swagout site, west of Paraburdoo

Driving back to Paraburdoo in the morning.  Our progress was slowed by cows along the road.  This is common.  I always slow down when cows are around  The last thing I want is to hit or be hit by a bolting half ton animal.  Well, these cows didn’t weight anything close to one thousand pounds.  Their ribs and hip bones were prominent.  They kept their heads down, eating the dead grass by the road, and ignored us.  This was unusual.  There were no calves.  The cows in Paraburdoo looked only a little better.  The carcasses and dying cow in Woongara Pool looked worse.

Seeing changes in the plants and these suffering animals made me realize that the Pilbara is a deeply hard place.  Setting aside the issue of whether large agricultural animals should be on this land or not, the margin between life and death is quite thin.  I have not often sensed this boundary.  All of the components that go into successful field work - advance planning, abundant supplies, good maps, strong vehicles, and a conservative attitude - insulate me from this viscerality.  Geez, I get twitchy if there’s less than five litres of water per person.  It’ rare that this cocoon of safety is pierced here or at any point in my life back in the Northern Hemisphere.  West of Para, it was dead evident.  This land will burn you, this land can kill you.  

NT Wildlife Park Spider

A picture, by request.  Sorry, I was not about to get close enough to this thing to insert a scale.  It was about the size of my palm, ~ 3 inches across.  Yikes.

Reading Core, Seeing Thrombolites

7/19: A cloudy Monday morning in chilly Perth, although the day promised to clear.  I’d arranged to spend two days examining drill core at the Geological Survey of Western Australia’s Core Library.  A core library?  Drilling core is one of the key ways that companies and researchers explore in areas where rock exposures are poor, or where what’s underground is of interest.  A rig drills a hole with a special diamond bit that leaves a long tube of rock at its center: core.  The core is periodically extracted, analyzed, and systematically stored in trays.  The average tray holds four to six meter-scale core pieces.  Cores are commonly several kilometers in length: a lot of trays.  Drilling core is expensive, and is mostly done by industry.  In Western Australia, the GSWA and companies have arranged for selected cores to be preserved: hence the Core Library, which makes core available for everyone to examine. 

The Library is in Carlislie, north of Perth City Centre.  I’d been there before, but didn’t quite remember how to get there.  Anticipating this, I’d rented a car (a Holden Barina, more on this later) which had a GPS.  Unfortunately, this Tom Tom unit was a bit confused about Perth and giving directions.  An example of its directions; “keep right, while bearing left”.  Louis eventually used it as an elaborate street guide.  This made getting to the library into another round of hunt and find.  We were good at this by now.  I prefer this game on dirt tracks rather than city streets. 

Once the Library was found, we signed in, went through the inevitable induction and quiz, and got to work.  I’d requested parts of four cores to examine, where I hoped to find the Paraburdoo Layer.  They were all from parts of the Hamersley Basin with poor outcrop; if we found the Layer in any of them, it would add greatly to understanding the Lauer.  Two cores were drilled by industry.  One was from a government project, part of a groundwater investigation.  The final core was actually a research hole, partially funded by NASA. 

The GSWA Core Library: that's "my" core in the center

The Core Library is essentially a very large warehouse with an adjacent examination area.  My four cores were laid out on several racks in the latter.  This is a Cadillac facility; the core was on racks that were at a non-back breaking height, the lighting was good, water and spray bottles (for wetting the core; textures show up much better this way) were available, and there was tea and coffee in the break room.  The only drawback was temperature.  The room wasn’t heated, since it was open to the warehouse.  Perth was a mite chilly in the mornings

We set to work.  Core was new to Louis.  I’ve not looked at it for a decade or so, but the technique came back rapidly.  It’s first a matter of staying oriented, i.e., knowing stratigraphic up and down, as one moves from box to box.  The real challenge is that rock in core looks very different from outcrop.  The core hasn’t been weathered.  For example, the tan to brown dolomites of the Paraburdoo in outcrop were gray in core, and their sugary outcrop texture (an indication of crystal size) wasn’t apparent in core.  In addition, as it grinds, the drill bit scores the outside of the core, which obscures and confuses the real features of the rock.  Core samples that have been cut with a diamond saw – the standard sampling method – can be similarly cryptic if the saw blade is worn or out of alignment.  So looking at the rocks was initially relearning and reorienting my mind to a new set of clues.  Louis picked the method up easily: no surprise.

We had two days to look at the four cores.  From reading core logs – the record made by the on-site geologist when the core was drilled – and talking with Bruce, I had a pretty good idea of where to search for the Paraburdoo Layer.  We set to work, starting on what I’ll call the NASA core, which had been nicely cut in half – with few saw cut marks.  Looking at core goes like this:

•  Spray the core with water. 
•  Bend over: the rules clearly stated that picking up core was not permitted, lest the pieces get out of order. 
•  Look at every layer with a handlens. 
•  Record observations in a progressively wetter notebook.
•  Try to stay warm through regular infusions of tea and hot water.
•  Repeat until the last box is reached. 

Louis looking at core

Actually, this is what I made Louis do, since he is a good observer with younger eyes.  There are much more sophisticated and technologically intense ways to look at core, but using eyes and keen minds was what we required.

I did a quick assessment of all four cores.  I soon discovered that two of them would be useless.  One started too far below the surface, i.e., below the level where the Paraburdoo Layer should be.  We’d visited the site where this core was drilled in the Hamersley Basin.  I’d actually stood on the capped well head.  The outcrop did not go low enough in the stratigraphy for the layer to be visible.  And now I knew that the core started too deep!  It was not surprising, but frustrating, to know that the Layer was probably buried a few meters below where we were working and camping.  Nothing for it.  The other core was a mess; the upper portion, where the Layer was likely to be, was a solution breccia.  The originally solid rock had been dissolved by groundwater into loose pieces, which had compacted together.  The open space between these pieces was filled with coarse crystals of calcite and quartz.  A very pretty rock, but useless for my purposes.  All sense of original stratigraphy and bedding was gone.  The core probably started too deep as well.

We motored along.  From my overview, I recognized marker beds in both “good” cores that I’d seen in the field; beds that were largely composed of chert (fine-grained quartz) rather than dolomite.  These were hints to the location of the Paraburdoo Layer.  It had to be lower in the core.  We looked hard.  I began to doubt my assessment and looked for the marker beds again.  They were there.  We looked hard a second time.

 

Lunch at a local lunch bar.  The Core Library was on the edge of a light industrial area.  Andy, the core librarian, had told us there were equidistant lunch bars along the road in front of the facility.  I picked left; out of the LIA and into residential Carlslie.  A sudden surrounding by small brick houses; the usual suburban variation in appearance, lawn decoration (no spinifex), and vehicles (no Patrols).  A quiet time of day.  I felt out of place; the house seemed small, and as I walked down the street, they seemed to converge.  Ah, the post-field work adjustment.  We came to the lunch bar, run by a happy Malaysian family.  More dislocation; I had not ordered a lunch in weeks.  A curry soothed.

I may have made the core examination process sound straightforward in my earlier description.  However, it’s often tricky.  Core is always fragmented.  This may happen for many reasons.  It may fracture as it comes out of the drill rig.  It may be broken intentionally to fit in the core trays.  It may split naturally along bedding surfaces or changes in composition.  Finally, it might be dropped when someone is handling it.  Not us; we were good, although for easier examination by Monday afternoon we surreptitiously started picking up pieces.

 

Louis marked interesting beds with pieces of paper towel.  In between my own examinations, I looked at these.  We were both finding the same thing: beds of dolomite that were the right thickness, and composed of tantalizingly, excitingly spherical-looking carbonate crystals.  I knew from my previous work that the spherules would really stand out.  None of these beds was right.  It was time for dinner.

7/20: We’d had the examination area to ourselves on Monday, except for one area blocked off by little orange safety cones.  The core trays beyond the cones were covered with paper.  Andy had asked us to stay away from this “confidential project”.  This of course made me curious.  On Tuesday, the paper was gone, and two people were working on the cores.  They were polite but distant.  I looked at the visitor’s log.  They were from one of the WA petroleum companies, which suggested to me that the core was from the Northwest Shelf of Australia, where there’s lots of natural gas.  As the day progressed, the Library staff gradually filled the rest of the tables with more core trays.  Based on their names, many of these also were from localities related to also petroleum. 

I was glad the petroleum geos were there.  They had gotten the Library staff to turn on a couple of large space heaters.  We got a pair too.  While being cold had sharpened my focus, it was making me too sharp.  The heat kept my head warm, at least.

We looked at the cores for a third time.  I revisited my stratigraphic assignments for a second time.  We looked at the core that was too deep.  No luck, no dice: the day was over, and we had a dinner date. 

Alas, no impact layers.  Well, the cores covered the right intervals.  We could not have looked any harder.  I’ve written earlier about why rocks don’t outcrop where they “should”.  Some of the same things may happen with core: removal by deformation or dissolution, nondeposition, or just bad luck.  In addition, since the core is broken, it’s possible a bed as thin as the Paraburdoo Layer may have fallen out of a core tray, or been destroyed in the drilling process.  I don’t know which of these possibilities were factors in my core reading. 

So went the official end of field work for Australia Fifteen.  I’d arranged to have dinner with my friend Carol in Fremantle.  I met Carol and her husband Shawn in New Zealand in 2006 when I was there for an Aikido seminar/holiday.  They’re both geologists; they moved to Perth to work in the minerals industry.  Shawn was unfortunately in the field. 

Getting to Carol’s house involved more GPS agony.  The Tom Tom failed to recognize both the district where she lived and her street name.  Louis navigated us to the general vicinity: then both missing localities suddenly appeared.  Maybe this is the place to comment on the Holden Barina.  Holden is Australia’s native car company.  It’s part of Ford at present.  The Barina is their bottom of the line compact car.  Ours was brand new, and it was a fine small vehicle with plenty of space for tall Americans.  However, it had two quirks.  First, the trunk had a propensity to open at random, which made backing down Carol’s winding driveway at night somewhat challenging, but amusing.  Less fun was the arrangement of brake and accelerator pedals.  They were at almost the same level.  More than once, I attempted to brake, and pushed the accelerator at the same time.  If the brakes had not been new, and I not an alert driver, this could have been dangerous.  I plan to tell Holden about this.

A satisfying Thai dinner helped to hatch a plan for the next day. Carol was free, and we had time and a car full of gas.  Three geologists and a car: what to do but something geologic?  I wanted to be tired for the long trip home; my flight left at 12:30am. 

7/21: Back at Carol’s house.  She’d consulted some friends.  Their suggestions made the day’s activity obvious: go see the thrombolites at Lake Clifton. 

Using a word like thrombolites means it’s time for me to get geologic again.  Thrombolites are a type of stromatolite, so let me start with the general.  Stromatolites are layered sedimentary structures formed by the combined action of cyanobacteria (photosynthetic blue-green algae and their brethren) and sediment deposition.  Basically, the cyanobacteria grow in lake or ocean water within the photic zone, forming a mat on the basin floor.  As sand and mud grains are deposited, or as minerals precipitate out of water, they are trapped in the mat, and in some cases also adhere to the cyanobacteria.  As they become buried by sediment, the bacteria grow upwards, trapping a layer of sediment.  Repeat and you get a layered structure: a stromatolite.  Thrombolites are a variation on this theme; they form the same way, but their layering is poorly defined. 

I’ve always liked stromatolites.  The word - stro-ma-to-lite - is fun.  Moreover, like iron formations, they are a remnant of an earlier earth.  Fossil cyanobacteria are among the oldest forms of life on Earth so far discovered.  These earliest fossils are a bit over 3.5 billion years in age.  They’re in stromatolites from the Pilbara, of course.  Three point five billion years ago – a billion years before the Hamersley Basin.  Until around 650 million years ago, when modern life forms begin to appear, cyanobacteria and stromatolites were the main players on the stage of life.  That’s all there was: simple, mostly unicellular plants, no animals. 

Given this, imagine an ocean shoreline three billion years ago.  The land would be barren; no life there, so no soil, just loose sediment and bedrock.  The rocks would be weathered, maybe slowly rusting; too little oxygen in the atmosphere (yet).  The sky would have been a different color (less blue?) for the same reason.  The only sound would be wind blowing among the rocks.  The beach itself would be coated with stromatolites, growing from the mean high tide line to below the surface.  The surf would be muted, the waves filtered as they coursed through the stromatolites.  That would be it.  A narrow band of life, taking advantage of sunlight and nutrients in the water.  I’ve always wondered what color the stromatolites were.  Probably dull greens to blacks: early plant colors.  Painting this sort of mental picture is what first thrilled me about geology. 

Stromatolites show a diversity of shapes.  I’ve implied a flat, matted appearance in my description above.  Stromatolites can also form domes, cones, or columns.  These forms can evolve into each other.  I’ve seen small cones on larger domes, and mats that morph into columns.  Stromatolites can be small- palm-sized – or large- bigger than an average car. 

Today, stromatolites are largely extinct.  They effectively vanish from the geologic record shortly after animals appear and diversify.  The paleontologists who have worked on this hypothesize that this disappearance is due to the evolution of grazing forms of life.  These animals ate cyanobacteria.  All those stromatolites must have provided free lunches for a while.  This is arguably the first mass extinction of life on earth.

With time, interest and exploration, remnant stromatolite occurrences have been discovered.  A surprising number of these are in Western Australia.  I’ve visited four of the five publicly accessible stromatolite populations, including Lake Clifton.  But hey, Carol had not been there.  Neither had Louis, and we just seen samples of the ancient Pilbara stromatolites.  I’d only been to Lake Clifton once, when the weather was windy.  I hoped for better viewing conditions.

Lake Clifton is south of Mandurah, an exurb south of Perth.  Getting there proved to be the final round of hunt and find for Australia Fifteen.  Like the Pilbara, having been there previously I had a vague memory of where to go.  There was one main road leading south from Perth, just like a dirt track in the Pilbara.  The navigational aids were vaguely useful.  The Tom Tom GPS covered the area, but refused to acknowledge the existence of Lake Clifton.  Carol’s road atlas stopped at Mandurah.  Again like field work, it was easy to know the way.  Keep the ocean to the right, stay on the main road.  Mandurah came and went.  I got a bit twitchy, as the coastal scrubland began to look familiar.  We were in need of water, junk food, and restrooms.  I sneaked a peek at a road map.  That’s right, Lake Clifton was in Yalgorup National Park, and it looked to be only about another twenty five kilometers to the south.  Relief.

Driving further.  A road sign: Yalgorup National Park, quickly followed by another: “Lake Clifton” with a right pointing arrow.  I turned on to a suddenly familiar steep road.  I knew where I was.  Right at the first T-junction, left at the second, go past the funky farmhouse, into the parking area.  A typical national park; dirt road, vague pullouts, chemical toilet, and a kiosk with maps and signage.  None of this had changed since my last visit. 

Having made use of all of these amenities, we followed the trail to the lake.  Lake Clifton is spring fed.  It’s networked to the cave system which underlies much of the coastal plain south of Perth.  In other words, no streams flow into it, so it is an isolated body of water.  I presume this is how thrombolites have survived here; grazers have not been able to get into the lake.  It’s possible that the water chemistry helps as well.

A nice wooden boardwalk extended into Lake Clifton.  The wind was light, the water fairly placid.  I didn’t get very far before stopping.  Instead of the accumulation of detritus (organic, inorganic, and human-deposited) that usually rings a lake, Lake Clifton’s margin was encrusted with thrombolites.  At the water’s edge, the thrombolites had broad circular shapes, and showed internal ring-like layering.  They looked truncated: I suspect that these are erosional remnants of no longer active thrombolites, which formed when the lake was a bit larger.  They reminded me of similar structures in Shark Bay, one of the other West Australian stromatolite sites.  I took pictures.  The light was good, sun low to the west.  Glad for the nth time to have a good circular polarizing filter on my Nikon lenses.  

Thrombolites close up - note the flat tops and concentric layering.

Lake Clifton thrombolites en mass

I walked further.  The thrombolites proliferated.  Their shapes became more clearly defined; individual domes, multiple domes joined together.  As the water deepened, the domes took on more conical shapes.  They did not get much wider, just taller.  This was eerie, as this change with depth was exactly what I expected to see; as the water got deeper, there was less wave influence, so the thrombolites could grow taller.  The thrombolites tops remained flat, like the ones nearer to shore.  Why?  Hmm, maybe this was a function of wave energy in Lake Clifton.  The thrombolites could not build up into the zone of water motion, so they were spreading.  Or maybe this reflects seasonal variations in lake depth.  I didn’t know the answer, but it was a pleasure to look and speculate.  The sides of the thrombolites looked fuzzy.  Allowing for dispersion in the water, I think this was caused by a coating of cyanobacteria. 

Louis and Carol iso the ultimate thrombolite picture

I walked around, took pictures, and shot video.  Within around ten minutes, I’d tried all of the obvious and creative photo angles.  It was time to stop and simply look.  Earlier in this post, I drew a mental picture earlier of a primordial stromatolite-encrusted shoreline.  Here I was, with a real colony of thrombolites.  This was one of the few places on Earth that I could actually do this.  It was a precious place.  A glimmer of the early Earth, and evidence of the tenacity and creativity of life. 

Well, my ultimate thrombolite picture

More Field Food Failure

When available, I eat fresh fruit at breakfast.  On the first shopping trip in Newman, I was thus pleased to see lots of apples and bananas on the shelves.  There were also green bananas.  I thought, hmmm; better get some of them too.  They should ripen once the yellow ones are gone or too bruised to eat.  So I added four green bananas to the overflowing shopping cart.  I put them in the breakfast food box, and forgot about them.

A week later, the yellow bananas were getting scarce.  I dug out the green bananas.  They still seemed hard.  I tried to peel one.  No dice.  I attacked it with a knife.  Slow going: I could barely pierce its now blotchy green skin.  I broke it in half.  It snapped when it broke, and smelled unbanana-like.  Definitely not ready to eat.  I put the remaining green bananas back in the box, wrapped in plastic.

The bananas continued to annoy me.  They were impervious to any persuasion about becoming edible.  I put them in the sun.  I added a ripe banana to their bag as a role model and as a source of ethylene gas.  I considered putting them on the engine block out of spite.  Field time was almost over.  Tactically, I began to ponder how to use them effectively in their unripe state.  The engine option was a clue.  Heat would be required.

Final swag out seemed to require a final dessert.  I thought about making fried green bananas.  However, when it came time to make dinner (my turn), I was very tired.  The effort of slicing bananas, exhuming the frying pan, heating margarine, and doing the actual frying seemed too taxing, especially when the final product was dubious.  I am sure we had enough brown sugar and honey to make any result edible, but in the moment exhaustion won out.  We had plenty of biscuits and chocolate anyway. 

I ran through this thought train while watching the fire, before cooking.  As Louis and I talked we expressed the mutual regret that we were not able to have a meal of Chernobyl Potatoes on Australia Fifteen.  When we’d last shopped, the Tom Price Coles store had amazingly been empty shelved with respect to root vegetables.  Sadness.  This conversation triggered mental synthesis.  Why not make Chernobyl Bananas?  This had many advantages.  It would use up aluminum foil.  The fire was not large, but we had plenty of wood to create coals.  It would be a lot easier than frying bananas.  It would be revenge.  Finally, it might work. 

I got the three remaining bananas, punctured each one, and wrapped them carefully in foil.  When the coals were sufficient, I made a cavity in the fire pit, inserted the bananas and buried them.  Of course, I had no idea how long it takes a banana to stew in its own juice, or even if bananas will cook this way.  I worked on dinner.  I checked one of the bananas in fifteen minutes.  It was still hard. 

Dinner was served.  I forgot about the bananas.  I assume Louis did too.  I remembered them oh, about an hour later when I caught a silvery glint from the fire pit.  I got the shovel and excavated all three bananas.  They seemed very light.  Their aluminum shells were intact, but stained with soot from the fire.  No steam came from the shells, only smoke.  I knew what was coming.  The shells cooled.  I pried one open.  At its core was a banana-shaped curved blob of carbon.  Oh well.

Opened banana on left; sealed on right

I don’t know if Chernobyl Bananas would have worked, given the right bananas and the right amount of roasting time.  Interestingly, the results of my experiment weren’t just blobs of carbon; the skin and tripartite sections of each banana were still distinct.  I don’t know what this means in terms of cooking potential.  In any event, while this experiment failed to produce something edible, it did succeed in using up supplies, enacting green banana punishment, and teaching me something about cooking.  And biscuits and chocolate is always a fine dessert.

Coda: Field Food Cleverness

Reverse the setting back to that initial shopping trip at the Woolworths in Newman. 

I wanted to make an Indian curry dinner.  No worries; Patak’s sauces are readily available in Australia.  While selecting a flavor of simmer sauce, I noticed packages of naan.  They were fresh, sealed in plastic.  I thought, hmm, can’t exactly be fresh, but would be a change from rice.  I added a package of garlic naan to the cart. 

Two nights later, swagged out south of Weeli Wolli, it was time to use the naan.  I’d looked at the package earlier in the day.  It recommended warming the breads before serving.  I knew this was preferable, for the sake of cuisine as well as thwarting staleness.  Two immediate warming options came to my mind:

1.  Heat the naan in the fire: temperature control would be tricky.     
2.  Warm the naan in my frying pan: it was small, and I only had a one burner stove.

As we found and parked at the swag out site, the solution came to me.  The Patrol had a turbocharger, which had a vent on top of the hood.  I check it.  Plenty hot.  I quickly took the naan out of its plastic, wrapped it in aluminum foil, and pushed it into the vent onto the engine.  This worked very well.

Naan - inserted

I made too much food.  Louis finished the naan at lunch the next day. 

Pilbara: The Second, Final Week

7/11: Woke up with the dull rumble of iron ore trains accompanying the usual bird song. Our swag out site was at most four kilometers west of the railway. It was somewhat eerie to hear engines in the night. Moreover, the rails would sing for quite a time before the train per se rolled by.

It was a good morning for a bush walk in search of spherule layers. There was a promising outcrop to the south. Only a couple kilometers of spinifex, desert pavement, gum trees, mulga, and wattles separated it from camp. I led a weaving path through the bush. It was clear, and warmed up quickly. I’m kind of glad it’s been dry; the density of spider webs has been quite low. No post-walk into the web spaz dance moves.

The outcrop disappointed. This is certainly the way of field work. From a distance, the rocks beckon. I am made hopeful of finding a spherule layer or whatever is my goal. But sometimes, no, commonly, the far view proves unreliable. Maybe there is too much talus; the outcrop is buried. Rarely, there is too much vegetation; it’s usually possible to move laterally and find an exposure. Most uncommonly, the layer I’m after simply isn’t there. Not in the sense that I can’t find it, but that it was not deposited in the first place. This is one of the fun challenges of sedimentary geology. Layers change from place to place, due to such causes depositional variations, topography, and chemistry. Understanding changes means making sense of the history, and that’s what I like to do.

The truck was out of site in the bush. A normal situation. Luckily the GPS knew where it was, at least in a straight line sense. While I don’t mind the adventure of finding my ride, I wanted to be on the road. With a dog leg to avoid some thick spinifex, we were in the Patrol and headed back up the power line road by late morning.

Food was low. Fuel was below 20%. We had less than 25 litres of water. A visit to Tom Price was in order. I drove down the railway access road. Bumpy, dusty, but by mid-afternoon we were back in my favorite Pilbara town. It was Sunday, but the Coles grocery was unexpectedly open. Wow, fresh veggies, fruit and ice.


7/12: I’ve probably written before that Tom Price is the “top town” in WA in the altitudinal sense, at 745 metres. This means potentially cold winter nights. I don’t mind chilly nights, but I dislike cold mornings, especially when the needs of nature force emergence from my swag. For this and other reasons I drove us south to Paraburdoo, in search of a lower, warmer swag out site. We found a nice site on Fortescue lavas west of town.

I’d made arrangements to look for the Paraburdoo Layer near the Paraburdoo iron mine, which is near (wait for it) Paraburdoo. Bruce and I had looked at the target section in the late 1980s. Jim Gordon, our contact at Rio Tinto, suggested that I just go look at it. But where was it, i.e., the access road to Radio Hill? I’d forgotten. I asked at the store where we bought supplies. The woman there said, ask Kerrie at the post office. I went to the post office. I didn’t see anyone named Kerrie. I asked the clerk who sold me stamps. She said, I’ll ask Kerrie. Kerrie appeared: she was the postmaster, an apparent fount of local knowledge. She said, no love, some bloke fell off the top of Radio Hill a couple years ago so now the track has a locked gate.

OK. I tried to call Jim: no answer. Did Para have internet? According to Kerrie, you bet, at the library. So at 9am Louis and I traded time online, sharing the library with a dozen Para mothers and their children. I felt large, smelly, and oddly out of place. Rio Tinto had come through for me. I had contacts at the Paraburdoo mine. I reached them on the phone. We arranged a rendezvous on Tuesday morning.

It was thus time for geotourism. With 3/4ths of a day remaining, there was adequate time to visit a pair of interesting sites west of Para. So back on the road. It’s a bitumen track all the way to Nanutarra. Relaxing to drive at 110 kph and not vibrate and bounce excessively.

I can’t resist writing the full geologic name of the first stop: the Meteorite Bore Member of the Kungarra Formation. The Meteorite Bore part has nothing to do with impacts; it’s the name of a nearby windmill; a groundwater pump. What’s cool about the Meteorite Bore is that it’s a glacial deposit. It’s composed of lithified mud and dropstones – pebbles, cobbles, and boulders – deposited on the seafloor by melting icebergs. At the time of accumulation this results a pile of mud with rocks in it. The technical name for this is diamictite. I like the way this term sounds.

Meteorite Bore Member

Since the glaciation that froze the water to make the culprit icebergs took place over 2.3 billion years ago, the Meteorite Bore Member rocks are not in the best shape. They’ve been metamorphosed. This compression squeezed the mud into low grade metamorphic rock. Since the forces involved were largely horizontal, the Member has a pronounced vertical fabric. The outcrops look like giant decks of poorly shuffled red-orange cards: big piles of rocks staked up end on. The dropstones are harder than the surrounding muds; they don’t deform, so they stick out of the rocks, similar to nuts in bread dough. Even neater, fins of metamorphosed mud have fused to each dropstone. When I picked one up, the hard rock – a piece of iron formation – was surrounded by a halo of compressed mud. I’ve never seen anything like this.

After contemplating the Meteorite Bore rocks for a bit, it was time to proceed to Woongara Pool. While only about eight kilometers from Meteorite Bore, it’s a thirty kilometer drive. Time was a bit short. I did not want to be on the road too late and up the odds of a road kill encounter with a roo or a cow. But hey, we were there. The track looked good. I didn’t see the sign at the gate that said “Cheela Springs Station – No Entry”.

Woongara Pool sits along the south edge of the Hamersley Basin, where deformation is greatest. The sedimentary rocks of the Hamersley Group at Woongara have thus been folded to vertical orientations. This makes a dramatic landscape. Woongara Pool sits in the fairly narrow Woongara Gorge. I hoped Louis would like it. The Patrol rounded the corner into the dramatic opening of the Gorge. The pool was mostly dry. Damn. There were dead and dying cows around it. Ugh. Well, the Gorge was still pretty in the afternoon light.

Woongara Pool, no dead cows in sight

7/13: I was sore after swagging out on a rubbly surface of Fortescue Group lavas. I’d sort of hollowed out a rock-free spot for my swag, but something poky still had conversation with by back during the night. Nonetheless, the rocks were interesting; very different from the usual Hamersley Group debris. Sandstone, lava, and white quartz – some sort of vein fill I suspect – instead of the usual chert, iron formation, and carbonate.

By the time we got to the security gate at the Paraburdoo Iron Mine, at 9 am sharp, I was alert. Time to chat up new geos and go look for the Paraburdoo Layer at a site I had not visited for twenty-three years. No worries. I called the geology office, and Jacqui arrived in about five minutes. She led us through Rio Tinto’s safety induction: a straightforward quiz this time. We both passed.

We waited while Jacqui fetched a truck. She returned with a graduate geo – a student – in the shotgun seat. Denzyl was on a break from Curtin Institute of Technology in Perth. This uni produces a lot of mining geos. Like Phil at Orebody 18, he was curious and avid to learn what we were about. We followed their Rio Tinto Landcruiser to the locked gate. I was pleased and touched at the preparations made for our visit. I’d anticipated searching for the drainage where I’d worked in the past, hoping that my vague memories would be triggered by the landscape. Bruce had sent me a couple of aerial photographs of our old sites, which I’d forwarded to Paraburdoo. The Rio Tinto geos had already reconnoitered the area; they knew just where to go. How nice.

As we left the track to Radio Hill and turned up an old route, the landscape did begin to look familiar. I recognized the hill I’d been on in 1986 when I’d watched a man and a woman load a trailer with slabs of rock. That was a weekend day; I presume the rocks ended up in a wall or patio in Para. The track degraded. We parked. I gave a brief spiel about what we were looking for. Both Denzyl and Jacqui looked shocked when I said that the Paraburdoo Layer was two centimeters thick. Sure, it was hard to imagine finding such a thin bed amidst the steep ridges of dolomite, spinifex, spider webs, and loose rock where I planned to look. There was to be a blast in the mine at 12:30. For safety, we had to exit this area by noon. I looked forward to a long day of up and down scrambles.

We started climbing. The dolomite exposures were pretty good, though badly folded and faulted. This was becoming normal. We climbed a ridge. The outcrop died. The next ridge to the east looked good. I led a short march over there. The dolomite bedding matched where we’d been, but I could tell that there was more continuous exposure here. I went up the drainage. I sent Louis over the ridge top. Denzyl and Jacqui followed me. I’d made Louis go the hard way. We chatted about life in Para, geology work in North America, and the Rio Tinto work culture. The drainage got steeper. I wondered how long we could all stand to look for the Paraburdoo Layer.

Then, like at the Governor last year, I just looked down. There was the layer. I said something to the effect of, I hate to make this look easy, but here it is. We’d been working for seventy-five minutes. I called Louis over, and we got to work, quickly measuring a section and taking samples. We were able to exit the area well in advance of the blast. That was easy.

Denzyl invited us back to the Geology office, where we met the rest of the geo team. Like Denzyl, they were curious and avid to hear about the project. I’d prepared a short talk for just this situation, so I gave it to them. Such a pleasure to have an intelligent and interested audience. I think they also appreciated a break from the routine of mine work. We said our goodbyes and left by early afternoon.

Back to Tom Price. We needed more supplies. It was time to ship rocks to the States. I dealt with rocks and gave Louis a shopping list. He came back quickly; unbelievably, the store was out of produce. Bugger, so much for Chernobyl potatoes! We eventually found enough palatable food for finish out the trip, and sent 12 kilos of rocks to the Northern Hemisphere.

My next goal was to get a shower. The closest hot water was in Karijini National Park. The sun was setting; no way to get there before dark. We ended up swagging out along the same track as last year’s rainy camp. Louis was pleased to see that the remnants of his rain shelter were still in place. This night, it was clear, the usual lovely shifting panorama of the planets and the Milky Way, punctuated by meteors.


7/14: I was dangerously close to having dreadlocks and flies were avoiding me, in spite of clothing changes and spit baths. I suggested that we camp at the Eco Lodge in Karijini. It had solar showers. Last year the Eco Lodge was the least appealing place I slept; the campsite was dirty, the neighbors noisy, the staff surly, and the showers cool. As we turned into the Lodge access road, I thought, how can they improve this year? This question was quickly addressed; the campground had burned. As learned later, a bush fire threatened the complex, so the staff preemptively ignited the grounds. The recent burn made the camping loops absurdly stark: a loose arrangement of caravans, tents, and vans on the brown and black earth. I thought, ugh, but maybe the water is hot.

In the spirit of being curious or optimistic, I booked a campsite. The young Aussie woman behind the counter gave me a site near the upscale part of the Lodge (canvas tents with raised floors and other amenities). This area had not burned off. OK, plus one. I checked out the showers. They were decently warm. Plus two.
It was late morning. After setting up camp, there was abundant day light left for exploring Karijini again. I’ve been here so many times in winter, what to do? I looked at the Park map, and found a few hikes I did not remember taking. Louis was amenable, so we headed first to Knox Gorge.

I’ve written extensively about the Hamersley Range gorges: deep clefts cut into the iron formation, up to several hundred feet deep. Each gorge differs, depending on the rocks making up its floor. If the base is iron formation, the gorge trends narrow and deep; if it’s a softer rock such as shale, it can be a broader valley. Knox was one of the broad ones. I think that the softer substrate also encourages plants; Knox was choked with gum trees, rock figs, bunch grasses, and wattles. The hike was a gentle walk among the vegetation, gradually opening out into pools with small waterfalls. Eventually I felt the urge to sit and take pictures, leaving Louis to continue through a large pool that required wading. He had been looking forward to this.

Knox Gorge

After lunch, we tackled Weano Gorge. I don’t know why it’s called Weano. This was a wholly different place than Knox. A steep descent and scramble down a talus pile led to the narrow gorge floor. There was no chance of getting lost here; the gorge was narrow, and all of its short side drainages quickly ended in chutes or cliffs.
Down and further down. Weano eventually reached a point where it was a couple meters wide, with an extreme drop off. This point was blocked by a whole gum tree trunk, which was jammed in the declivity. The flood that brought these remains here – stripped of small branches and bark- must have been epic. This was as far as we could go without technical equipment. The sun shone on the cliffs through the cleft; this produced a vertical ribbon of orange light framed by the horizontal layering of iron formation. It was good that I had carried my tripod.

Weano Gorge

A shower, finally. I enjoyed removing a layer of grime from my skin, and was surprised to discover a bit of tan underneath it, in spite of all of the sunscreen and dust I was also wearing.

A good dinner led to a short hike, an epic search for the camper’s dishwashing station. Harder to find in the burned off area in the dark: no paths. The relative abundance of civilization suggested that it was a good night to indulge a tad. I went to the lodge to buy a couple drinks. The guy helping me was the only other American I met on the trip. He was easily the rudest person I met. Maybe this was in contrast to the average gregarious and helpful Aussie, or maybe it was his personality. I hope people thought he was Canadian.


7/15: My morning walk was through the burned bush. It was barren but moving. All of the burned trees, shrubs, and grasses were resprouting. The way of an ecology of fire.

One gorge left: Kalamina. An early start guaranteed some quiet time in the gorge. This was rare. It’s school holiday time in Australia. The Eco Lodge had been rich in families as well as the usual travelers: twentysomethings, adventurers, pensioners, and the odd geologist or two. Interacting with Australian families is interesting. In every instance I can remember, only the father/husband talked to us. The women would smile, but rarely converse. Was this because we were guys, or does it reflect some Aussie family dynamic? Most families also consisted of two parents and three children. This grew to be uncanny. I could consistently predict whether a family was Australian or foreign (mostly Europeans) based on the number of kids. This pattern was consistent in the NT and Kimberley. Kalamina Gorge attracted lots of families. I talked to fathers from Port Hedland, Perth, Drobbo, Tom Price, and Brisbane. It takes valor to drive across Aus in a campervan with three small children, that’s for sure.

Kalamina Gorge

 More Kalamina Gorge

7/16: Time to go back to work. I’d spent the afternoon at Fortescue Falls in Dales Gorge, writing this blog. Louis went walkabout. I generated many surprised stares as I sat typing, with my feet dangling over the big pool. Cognitive dissonance, my pleasure.

Australia Fifteen had taken me to the western, eastern, and northern margins of the Hamersley Basin. Only one direction was left. Luckily, there were mapped outcrops of Wittenoom Formation available in the far south. Another remote area of the Basin, which I’d never penetrated. The rocks at the southern margin have crumpled into tight folds, courtesy of the same mountain building event, the Capricorn Orogeny, that I’ve mentioned before. The peaks are higher here, well over one thousand meters. I needed no more rationales to go for a look see.

The most promising area was southeast of Mt. Hilditch, named for Len Hilditch, the prospector who discovered the ore deposit at Newman. An adjacent peak is Mt. Ella, named for his wife. Why not Mt. Len? The Hilditch’s old prospecting vehicle is displayed at the Newman Visitor Centre. It’s a 1950s 4WD; a raw piece of machinery. I admire the courage, individual and relationship stamina, and hope it must have taken to poke around the Hamersley Basin in the fifty years ago. This was before quality maps existed. Bad tracks, hard living, and unknown territory. Running up hills to see their rocks. Hmmm, that actually has a certain appeal.

Anyway, the direct route to Mt. Hilditch was blocked by the West Angelas iron mine. I outlined a dog leg route around this via Giles Point – named for Ernest Giles, the first European explorer to travel the Pilbara. I fully trusted Louis to navigate us in while I focused on the road. The Giles Point track is another old route like the Pannawonica-Millstream road. It was in surprisingly good shape, courtesy of many recent exploration tracks that slashed off it across the bush.

We cut across Wanna Munna Flats. The bull dust was thick in places, making the Patrol fishtail a tad and leaving a suspended cloud of fine red dust in our wake. After an hour, Mt. Ella came into view. The track remained good. We took a short pass to the north, and turned west towards Mt. Hilditch, only to see the tailings pile from the West Angelas mine. Tailings had been spread further south beyond any reasonable expectation. I wanted to avoid active mine areas at all costs. What to do. Well, the Patrol looked official, so I turned on the beacon light, lit the headlights, and drove on.

The track turned south, and abruptly climbed. I was able to downshift rapidly, avoiding any traumatic need to use the low range gears, or roll off the hill. The track wound into the valley I’d targeted. I could see promising outcrops to the north. After some prospecting, we found an old track that wandered the right direction. Lunch and a hike. I set off quickly. The landscape was pretty rugged and spinifex-laden. This was no place to swag out, so a mid-afternoon departure was indicated.

I came to the first outcrop. Crap. It was a blue-black, fractured, and badly ferruginized chert. Not a good sign. This lithology often indicates poor exposures and bad preservation of the sort of information I am interested in. Pressing on, the next exposure was no better. It was a thick accumulation of surface weathering deposits. From the truck, it had looked tantalizingly like a dolomite outcrop. No Paraburdoo Layer here. Well, the cliffs still looked promising for the Bee Gorge Layer. The hills were a challenging climb, even for the Hamersley Basin. Steep and treacherously covered with loose rock, just enough to make balancing difficult. The outcrop improved. I began to hope. I passed through the last good marker bed below the Bee Gorge Layer. The outcrop died. Bugger. We poked around for a couple hours. No joy.

Redemption occurred during egress. I’d spotted another promising exposure right by the track, within distant sight of the mine tailings pile. A five minute hike and we were on the Bee Gorge Layer. A good continuous exposure. Easy. This simplicity raises a question of geologic philosophy. I had driven past this outcrop en route to the futile site at Mt. Hilditch. Was it necessary to struggle first before this easy find? There are many answers to this, take your choice from karma to the Protestant worldview to my own stubbornness.

A final swag out in the Pilbara. Where to have it? Not near Mt. Hilditch. In addition to the spinifex issue, there was certain to be the constant rumble of the West Angelas mine. We returned to the east, eventually finding a good clear spot on the flats. I regret last nights in the Pilbara. A good camp, a decent meal, the standard fantastic sunset, and a night of stars help, but also make the ache worse.


7/17: The last field day dawned as normal. Incipient light in the east. The stillness of bush night giving way to bird song and the rush of a slight breeze. The first sunlight touching tops of hills and trees, golden and brightening. Spotty clouds drifting down from the northwest. It was decently warm. I wiggled out of my swag to enjoy this beginning.

Australia Fifteen had successfully reached all of my target areas. My planning had included leeway for the unexpected. This day looked like one of these times, only the unanticipated part was – what to do rather than go to Newman and begin the civilization reinsertion process? Eagle Rock Falls sounded interesting and photogenic, and it was on the way.

We packed, buried the fire pit, found the track, and headed east past Giles Point. When I’m driving in the Pilbara I always track the stratigraphy in the hills around me. It’s become second nature. The mountain east of Giles Point looked very intriguing. Louis sensed it too. I took another glance through the trees. Whoa, there might even be dolomite over there. Eagle Rock Falls suddenly seemed much less interesting.

Park, gear up, boot up, hike out. There was certainly lots of dolomite exposed. I began to hope that we might find the Paraburdoo Layer. I found a drainage that seemed to have the thickest dolomite exposure, i.e., the most rocks visible, and started looking. Typical scratchy deeply weathered cryptically layered stuff. I examined every bed. Louis did the same. Moving upwards, I recognized some of the marker beds I’d found in the Paraburdoo. The Layer should be below them. I worked back downhill. The outcrop remained tantalizingly promising. We couldn’t find the bloody thing. Time to move uphill, searching for the Bee Gorge Layer. That should certainly be exposed… But a repeat of Mt. Hilditch ensued. The outcrop died, inconveniently. We searched until exhaustion, hunger, and the need for a shower overruled the hope of success.

It was interesting to examine such a promising site and not find either of the spherule layers. There are plenty of good reasons for such non-success:

1. The layers may have been buried.
2. They might have been locally removed or rendered unrecognizable by deformation.
3. They might have been visible but simply different in appearance.
4. Louis and I might have been too tired and just missed them.
5. They might not have been deposited here.

I’ve listed these hypotheses in order of decreasing likelihood. So was the time at Mt. Giles failure? I usually feel tense at a new site until I find what I’m after. Did I pick a bad place to search? Am I wasting my time and resources? Am I not good at what I’m doing? I felt these anxieties and others many times during the work of Australia Fifteen. I’ve had similar and stronger feelings during my past field seasons. This year, they mattered less. Oh well, I didn’t find the damn layers, but I could not have looked any harder for them. Wherever I went, I learned more about the Paraburdoo Member of the Wittenoom Formation; building this mental map was both fun and satisfying. It was just fun to be out there trying.

I haven’t answered the failure question. It’s not a binary choice. I’m sure on some grant report the work at Giles Point will reduce to a dot on a map indicating no spherule layers were found: non-success. But on the larger scale, I’ve have the satisfaction of poking into a new place and examining it with my best effort. The process is a sufficient result.

I didn’t worry this too much on the drive back to Newman.

7/18: Goodbye to the Pilbara via an early afternoon flight. Hello to Perth: chilly, strikingly humid, and suddenly full of the diverse rush of human activity.

Pilbara Road Encounters

It’s been as strange year for driving in the Pilbara. Here is my evidence. As preamble I should say that outside of a town it’s extremely unusual to see anyone on a road without a motor vehicle nearby.

1) En route from Range Gorge to Pannawonica, I’d driven for two hours across the Chichester Ranges and seen exactly three vehicles. We came over a rise. There were two women jogging on the road. They were clean, wore nice track suits, and looked quite happy. They waved as we drove past. I tried not to cover them in dust.

2) We were sitting on the Jimmy Creek road eating lunch; out of the spinifex. Louis said, there’s some one on the road. I looked up to see a woman walking towards us. She came closer. We waved. She waved. She was Aboriginal, but dressed in safety clothes. After greetings, she wanted us to understand that much of the land behind us was an Aboriginal religious site. There were certain areas we could not go. No problem there. She thanked us and walked away. I later sighted a power shovel and truck working to the east about a kilometer. Maybe she walked over from that operation.

3) Earlier the same day on the same track, we drove past a Thrifty rental truck parked on the verge of the road. As I slowed to pass it, a helicopter suddenly took off from nearby. It headed to the top of a nearby mesa and landed. It eventually flew on to the east. I assume some one got picked up near the truck. We stayed in the area the rest of the day. The helicopter never returned.

4) We drove in Paraburdoo. The main street was blocked by cows. It was a clear sign to leave town and camp. When we returned the next day for phone, groceries, internet, and lunch, I inquired about this at the AusPost. The cows were in town because that’s the only place in the area where there’s forage. Paradurdoo’s common areas and many lawns are keep green using groundwater, unlike the surrounding parched regions. The cows were simply trying to survive. Apparently there had been many more around until the previous week, when Rocklea station mustered them out. Paraburdoo would have been quite an exciting place if this involved the usual helicopter and station hands in trucks.

5) On the way into the Mt. Hilditch section, my target was putative dolomite outcrop about ten kilometers southwest of the West Angelas iron mine. I wanted to avoid the mine site; easier for everyone. The track ran through a gap in the hills and turned west. Directly ahead as a massive tailings pile from the mine. It had expanded beyond all expectation. Luckily the Patrol looks like a mine vehicle.

6) I held my breath wondering how to end this post. What would the land provide? I cringed at the idea of having to manufacture something that fit this narrative. Provision occurred. After a final swagout, we drove west on the Giles Point track towards Newman. It’s one of the old Pilbara roads, now used for mine exploration and station work. It’s in good shape, but has serious patches of bull dust. I drove the Patrol through one of these soft patches at a sharp curve in the road. I looked to my right, checking the berm height, and saw a flash of purple.

The turn in the road: the bush just left of center

I stopped. It was a Common Fire Bush in flower. Wow; it’s early in the season and it’s been really dry, so flowers have been very rare. One of my loves of the Pilbara has been its flowers; so diverse, so fecund. The Fire Bush was lovely. It was covered with blooms and about-to-be blooms. It was a stark and welcome contrast to the harsh dryness of the Pilbara this season.

Common Fire Bush, close up

On to the Pilbara: A First Week

7/3:  quick flight to Perth, adios to Paul, hola to Louis. 

7/4: Eighteen hours in town, chilly in the morning, close to zero.  A late morning flight to Newman.  I chatted with a gent who worked as a safety trainer for a bunch of the mining contractors.  He was also in the Australian Navy Reserve, and Commander of the Sea Cadets.  He had many interesting stories. 

Newman and suddenly the weather was temperate again.  I found the truck – vehicle number four of this trip – in the car park.  It is a Nissan Patrol, which I had expected with some regret.  It’s Landcruiser Lite –a powerful engine and plenty of truckness, it’s not as taut in the gearbox or suspension as the Toyotas.  No worries – this will keep me from getting too far off road.  It was Sunday.  All of the town businesses save for the pub were closed.  We sorted gear and packed the truck.

7/5: A return to the end of last year’s field season: the gate at Orebody 18.  Last year, they pretended I had not been in contact.  This year, Phil, a BHP geo, was there to meet us within fifteen minutes of contact.  He was a young bloke, a mine geologist.  He and a couple other geos had been intrigued by the project.  Too bad only he was available on Monday. 

Our first stop was to gather safety gear and read a safety briefing.  All of the companies have gotten very serious about this, which is a good thing I suppose.  It’s a bit strange to see the uniformity of all staff in safety gear all the time, even the receptionists. 

I read the briefing materials after rolling my shirt sleeves down, as requested, to comply with the safety code.  I signed on the appropriate line.  I handed it to the safety officer.  She said, you didn’t fill it out.  I said – huh?  It was a quiz.  Oh.  This wasn’t apparent, but now I’ll never forget that I should call for help on Channel 84.  We put on our safety vests, hard hats, safety glasses, and stowed our gloves and ear plugs, and headed out in Phil’s truck. 

I had not been to this research site for nine years; on that visit I was jet lagged so it was a haze anyway.  Nonetheless, the scenery began to look familiar.  We parked, and within thirty minutes I’d found the spherule layer. 

It’s remarkable to me that my long term memory retains the visual map of this spot in the Pilbara, much less that I can so unerringly look at the rocks anywhere out here and find what I am after.  If it were possible to quantify the last twenty-five years, I’ve spent relatively little time in the Pilbara, and even less looking at its rocks.  Yet this place is ingrained in me.  I don’t think I’ll ever loose the capacity and knowledge of here.  I suppose this is true of places that are significant in one’s life.  My time here has consistently been a catalyst in my maturation through the various stages of life.  That has to help.

Anyway, Phil was delighted to see the impact layer and hear about how we think it formed. He waited patiently while Louis and I did our work.  We were off-site – free of safety gear and able to take risks again – by early afternoon. 

The shops in Newman were open.  $450 later, we had enough chairs, ice, gas, food, water, and other random gear to last a week or two.  There was still time to drive west on Rt. 95, shoot the gap north through Cathedral Gorge, and swag out off of the track to Weeli Wolli. 

7/6:  Oh, the pleasure of a first night under the Southern Cross, with the only noise the very distant murmur of road trains.  A partially cloudy sky; the weather seemed unsettled.  Louis was still asleep.  I got up and stared at the back of the truck.  Well, I opened it first.  I’d quickly sorted and packed all of the food, water and gear the previous evening.  With each new vehicle, it’s a geometric challenge to fit everything in ways that don’t rattle, abrade the truck, or cause self destruction.  It’s was made a bit more challenging by the second spare tyre, which hogged a large inconvenient section of storage space.  However, the current set up of the Patrol looked pretty good, although the chairs, shovel, and stove seemed ready to fall out.

After breakfast, I drove us on to Weeli Wolli.  This was another return to the scene of the crime from last year, only this time I was in search of the new spherule layer.  With minimal effort, we found the track we took to the research site last year.  It was a rubbly and rough drive, but at least there was a track.  We eventually came to a reasonable outcrop of dolomite; the main type of limestone that makes up the lower Wittenoom Formation, where the Paraburdoo Layer is located.  I don’t know these rocks as well. They are poorly exposed, and when you do see them, they comprise thin layers of brown laminated rock.  Yawn.  Nonetheless, it was time to learn them, in order to find the Paraburdoo Layer. 

Weeli Wolli is a fairly large drainage, typical of the southern Hamersley Basin.  It occurs in the soft rocks – the Wittenoom – and takes advantage of the abundant folds and faults in the area.  To us, this meant that the dolomite exposures we looked at were isolated hill-sized blobs.  Well, time to work with what nature provided.  We worked uphill.  The dolomite began to show a consistent stratigraphy that we could trace from outcrop to outcrop.  This was a relief.  However, we couldn’t find the spherule layer. 

I could tell that the dolomite continued downhill and across the creek from where the truck sat.  Near the northern edge of the drainage, there was a nice ravine with good outcrop on both sides.  This seemed like a good target.  After lunch we set out.

Back to walking on rubbly stumbly outcrops, through and around spinifex, and scrambling down cliffs.  My route hit the main Weeli Wolli drainage.  It showed evidence of recent flooding; large gum trees lay horizontal in the channels, their roots and branches packed with debris.  The bare dolomite outcrops were polished and scoured.  Large bars of gravel and cobbles partially covered them, and made walking tricky. 

We made it across, and got to my target ravine.  I left Louis there to look for the spherule layer, while I walked uphill to tie us into the stratigraphy we’d looked at earlier in the day.  Of course, I went slowly so I could look for the spherule layer.  This means staring at every visible bed, a slow process. 

I performed my once-a-field season fall into the spinifex.  A couple dozen punctures in the left hand and arm, oh well.  I’d climbed high enough, it was time to turn around and find Louis.  I figured, we’d looked hard, but no layer, no regrets.

When I got back to the ravine, he waved something at me and mumbled indistinctly (a trend).  Eventually I understood that he’d found the layer!  A few very minimal outcrops at the top of the cliff on the south side of the ravine.  I was suddenly happy, and forgot the allergy-induced fatigue I had been suffering.  We had a look.  Definitely spherules.  I was bemused to have a new spherule section.  I’d essentially assumed we would not find it at Weeli Wolli.  I was happy to be surprised.  It reinforced my faith in serendipity.  If I had not gone on walkabout, and Louis weren’t so thorough and inclined to scramble up cliffs, we would have never found the one centimeter of spherules at Weeli Wolli.

7/7: The morning entertainment was a several hour drive from Weeli Wolli to my next site, Range Gorge.  More time north on Rt. 95, then west towards Wittenoom from Auski.  Range Gorge is one of the series of steep valleys that cuts the north side of the Hamersley Range.  There are no tracks into it, nor does it have access from Karijini National Park.  However, an exploration company drilled a research core here in the late 1980s.  I’ll look at that in Perth next week.  I wanted to come here to look at the above ground part of the section, in the hopes of finding the Paraburdoo Layer. 

The first challenge was to find the twenty four year old track to the drill site.  A new berm on the site of the road made this tricky, but with some high torque from the Patrol, we succeeded.  I was pleased to see that the drill site, the outcrops of dolomite behind it, and several hundred acres of the surrounding bush had recently burned.  Bare rock, burnt bushes and trees, and the ashes of spinifex – what’s not to like?  It was dramatic.  The bare rock of the plain ended right at the first cliff of dolomite; a xeriscape without the plants (currently). 

More dolomite, only this time a straightforward bottom to top section to see and learn.  I again put Louis to work at bed by bed examination, and went climbing to get perspective on the overall stratigraphy.  My coordination was a bit dicey from my allergies, but I looked, climbed, and eventually got oriented.  I’d managed to climb an isolated knob.  In the 180 degree view in front of me the Hamersley Range continued to rise.  There were a series of intriguing rock overhangs in the cliffs right below me.  I immediately thought: Aboriginal sites?  To the right (west), Range Gorge cut into the cliffs, its incision making a broad alluvium- and gum tree-filled valley.  It was a big drainage.  I wanted to walk up it and see what was there.  Maybe very long day hike In the future?  The Fortescue River plain filled the scene behind me.  Broad, flat, and mostly burned off from my vantage.  The Chichester Ranges were barely visible on the horizon.  I loved this view. 

Louis had not found the layer.  We worked it over together.  It wasn’t there, or was hiding really well.  Actually, there were a number of thick landside beds in the dolomite, which is unusual.  Their presence meant that the Paraburdoo Layer had to be deeper underground.  I hope we can find it in the core when we get back to Perth.

Our work done, I suggested a walk to look at the overhangs I’d seen.  We scrambled up the burned over drainage.  There was still plenty of loose rock.  The overhangs were all at the top of steep talus piles.  They turned out to be kangaroo hostels, based on the tracks and droppings covering the area.  If the Aboriginals used these sites, they did not leave any evidence. 

Time to explore was good.  This is one beneficial aspect of this research project.  The rock unit we are looking for is so specific that I can definitely say we’ve looked hard for it, time to cease.  Projects covering a broader areas require more self-control.  It’s thus a luxury to have energy and time for a post-work stroll in the bush.

7/8: A cloudy morning, especially in the west.  That was our direction of travel.  I thought, a good day for driving; my plan was to commute to the west edge of the Hamersley Basin, where there was a potential Paraburdoo Layer exposure.  Escaping from Range Gorge, I pointed the truck west on the Wittenoom-Pannawonica road.  Time to sit and drive, racing over the Fortescue River floodplain at maximum safe speed.  A landscape covered with mulga and gum trees; frequent cattle sightings too.  We passed the Mt. Florance Station turnoff.  Coolawanyah Station was next.  Coolawanyah had done a particularly nice job marking their turnoff, using a pair of nicely painted tractor tyres. 

A pause at the Rio Tinto railway to watch an ore train roll by, headed north.  A bit more than a kilometer long.  I lost count of the number of ore cars.  All that rock, going to China, Japan, Taiwan, and Korea.  I wonder how many of my home appliances are made with Pilbara iron ore? 

The sky was darker.  I could see rain bands in the west.  Oh crap.  Nothing to do but drive onwards.  A light sprinkle began at lunch time.  Good, the Patrol windshield wipers were in decent shape.  The rain got heavier.  I was relieved we were on a main track.  It was unsealed, but the surface was well-compacted so it wasn’t immediately going to turn into a sea of red mud. 

I had to put the wipers on high and slow down.  Water began to puddle on the road.  About forty kilometers from Pannawonica, the sky lightened.  The rain stopped.  The wet track was doing just fine.  I slowed for the numerous muddy patches.  Splash!  Oops, that big puddle was more of a pool.  The white Patrol was now largely red, up to about mid-window height.  No worries, we did not loose traction.

Stopping in Pannawonica seemed like a good idea.  I wanted a tarp for weather security.  Panna is another mining town.  It was founded in the early 1960s like Tom Price and Newman.  Its independent operation was absorbed by Rio Tinto in the 1990s.  It’s a small place.  Luckily the store had a tarp, bread, and the other few things that we needed.

OK, the clouds seemed to have dissipated, but where to go?  I saw a sign that said Bungaroo Project, pointing south down a wide track.  Hmm, Bungaroo Creek was pretty close to where I wanted to look the Paraburdoo Layer.  The track was good, built by Rio Tinto.  Definitely for exploration; roads cut off from it at intervals to drill sites.  We eventually found a old, unused side track and swagged out. 

The clouds gradually returned.  We were at a relatively low elevation at 360 meters.  It was warm and after the rain, strangely humid with a strong smell of damp rocks.  We swagged close to the Patrol, and prepared for a quick evacuation.  I fell asleep right away.

Only to wake up with rain falling on my face at 12:30 am.  Time to bolt.  We threw our stuff in the Patrol and headed back to the main road, stopping just at the berm.  Slow, somewhat anxious driving through a heavy downpour.  Parked, we sat in the truck.  The downpour stopped.  Louis bravely set up his tent.  I went to sleep again, in the driver’s seat.  No worse that economy class on a Qantas 747.

7/9: I woke up at 4 am.  The stars were out.  I spread out my swag and got a bit more rest.  Dawn and the weather looked a bit more settled.  Still partially cloudy: numerous blue patches.  The brief storms had soaked the ground to a depth of six centimeters at most.

We went in search of the old Pannawonica to Millstream road.  When I came to the Pilbara in 1985, this was the main route from Wittenoom to Panna and beyond to the coast road.  The Bungaroo Project road had bisected it somewhere.  I’d missed it the night before in haste to make a wet swag out. 

This trip has been much more about hunt and find than Australia Fourteen.  We’ve done all the easy sites.  The project has pushed into the peripheries of the Hamersley Basin: more remote, old, and less traveled tracks.  Finding the old Millstream Road is a good example.  It was on my Pilbara Tourist map (1:1000000 scale) and on my topographic map (1:100000 scale).  My GPS, which includes the topo database, showed us where we were: not on the Millstream Road.  However, this was useless.  We could tell the geographic direction to go, but which route to take to get to it?  All of the new mining tracks weren’t on any map or the GPS.  Finally, I decided, let’s just try this one: a straight track, probably a mining survey line, plowed through the bush.  It cut the Millstream Road in about 2 kilometers.  The GPS confirmed our location.  Easy continued.

I’d wanted to find the Millstream Road in order to get to the Jimmawurranda Creek area.  I’d been there in 1985 with Bruce, and subsequently for some of my Ph. D work.  It had dolomite.  Thirty kilometers of damp dirt track, and a couple road encounters (see a future post) later, wee found a good site.  It was mid-morning.  The sky was clear enough to seriously boost my morale.

This project requires optimism.  As I wrote in the introduction, the Paraburdoo Layer is at most a couple of centimeters thick: fingernail-scale.  Imagine trying to find this amidst discontinuous outcrops, talus, spinifex, faults, fold, streams, and other complexifiers and the need for hope should be clear.  One helpful bit is that the spherule layer weathers to a grey-green color, which is unlike the usual brown dolomite, black to grey to ochre to red cherts, tan shales, and green volcanic rocks.  Unless of course, any or all of the above are covered by an orange-red iron stain, whitish caliche, or purple-black desert varnish. 

Does this mean I’m an optimist?  Well, at minimum I’m persistent.  I like the feeling of success.  There is also the hope of finding something new, unusual, and exciting.  This is also a great excuse to be outdoors, in Aus, and looking at rocks.

We went south of the road.  Lots of dolomite exposures, along with abundant folds and faults.  Déjà vu for the Weeli Wolli sections.  However, just like that site, my observations began to crystallize quickly into stratigraphic patterns.  Ok, these two black chert/golden carbonate sequences are here, above the think dolomite beds…  Intensely creative and useful as long as I wrote it down. 

Lunch and time to work to the north.  It seemed a good idea to pick a campsite first.  The bush was thick and unburned throughout the area.  I think it always has been.  This meant that best bet for swag out was a stream drainage.  Drainages always have plenty of wood stacked up from past floods, a reasonable sky view for star patrol, and the stream sediments are often softer than typical Pilbara soils.  So how do you find a good place to swag out in a stream?  Bruce and I evolved the following technique in the late 1980s:

1)      Aim the truck along a fairly wide drainage: one that’s pretty open, where there’s potential to get far of the road.

2)      If tyre tracks exist, follow them.  They usually mean some one has successfully followed the drainage, and returned (hopefully).

3)      Bounce along as far as you can stand, trying to control the truck as it groans in 4WD over bars of sand, gravel and small boulders.

4)      Back up frequently to avoid drop offs that would bog the truck.

5)      Get tired.

6)      See the right place to stop: room for swags, a fire pit, a kitchen, and the truck.

7)      Park, fall out of the truck and recover.

Louis and I did this.  He’s initiated now. 

The rocks to the north called.  We walked several kilometers and looked at a dozen outcrops.  The rocks showed the same sequence as south of the road.  Interesting but disappointing; we were not getting any deeper in the stratigraphic section, meaning that the Paraburdoo Layer was buried.  Just like Range Gorge

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7/10: I’d driven at least 760 kilometers since July 4^th, mostly on unsealed roads.  A good night’s sleep in the Jimmawurranda Creek drainage had helped, but I was still tired after the rainy night.  Louis was developing a cold.  My allergies were fading but still taxing.  Another long drive was next on the agenda.  It seemed like a good time for a break.  We followed the Millstream Road to Millstream.

Millstream is a part of national park.  It’s historical; Millstream Station opened in the late 19^th century as a cattle station and sheep station.  The sheep didn’t last, at minimum because dingoes find lambs to be delectable.  The cattle station persisted into the 1980s, when the government took over the lease, i.e., no more cows.  Well, this is the colonial history of Millstream.  The station site was a in a logical site because it is where a major aquifer breaches to the Earth’s surface.  This has formed fairly permanent spring-fed pools.  Of course, the Aboriginals knew this was an important place a good 20,000 years ago.  New signs at the station indicated that Millstream has been an important gathering site for a number of different groups for at least that long. 

I was happy to be someplace that was verdant and wet.  We had enough energy for a couple of short walks among the pools.  It was quite strange to hear and see running water: well, water running on the ground, not falling from clouds.  Millstream had a real feeling of oasis.  This was most poignant at the lily pond; a pool full of flowers, seeded there by one of the station women over one hundred years ago.  I’ve never seen wild water lilies before. 

Most of the large Millstream pools follow old channels of the Fortescue River, creating long curved water bodies.  A swim in one of these was indicated as a pre-lunch activity.  I jumped in, and happily floated in the cloud of dust, sweat, and grime dissolved from my skin as I paddled about. 

Back to work.  More dolomite called to the south, along the Hamersley Front.  Back to hunt and find.  Ok, Millstream was on the maps, so we knew where we were starting from.  How about this track?  Damn, a “Pastoral Lease – No Passage” sign, hand lettered in green paint on a sheet of corrugated iron.  It didn’t say which station this was: no one to call about access.  OK, let’s go seventeen kilometers and try this one.  A locked gate, another hand lettered sign.  This trend continued monotonically.  I was annoyed and somewhat frustrated; the day was passing, it was time to find a swag out spot. 

The road intersected the Pilbara Iron railway line (Karratha-Tom Price-Paraburdoo).  I’d gotten an access permit, so we headed south along the tracks.  More locked gates.  Finally, the power line road, following the same trend as the railway, but here cutting across the bush – pretty close to a dolomite exposure.  We took it.  We swagged out close to the Front, in hopeful site a good outcrop for the next morning’s work.