Wednesday, July 1, 2009

Pools, A Roo, Spherules

Today was unusually intense and interesting. After a day of hiking and photography in Karjini National Park, we had to swag out last night in the overflow camping area near Dales Gorge. Who knew that June was the busy tourist season? It’s not as full later in the winter. The area was promiscuous: a stereo pair of banal late night conversations kept me up.

I woke up severely crabby. To compensate, I got up pre-dawn as always. I resisted the temptation to 1) slam the Cruiser doors, 2) rev the engine, and 3) set off the reverse gear, parking break, and headlight beepers (they are each loud, and not sonorous). I walked down the old Yampire Gorge road. It washed out in the mid 1990s. Like Wittenoom Gorge, Yampire had asbestos mines, so the Park never repaired the track. Fine by me. Nice sunrise, partially cloudy, so the scarlet-pink-orange-lemon-yellow transition of the sky made me smile.

I love watching the bush warm up in the early light. The spinifex glows a little greener and a bit yellower. It’s been damp enough that the desert pavement is covered by light dew. The purple-red sand gravel sparkle; this fades as the water evaporates.

Dales Gorge. This is one of the best sites to see banded iron formation. Here, the Dales Gorge Member of the Brockman Iron Formation is exposed. It includes one impact layer. I wanted Louis to see this. It’s also a really nice place to hike.

The gorges in Karijini aren’t that deep, maybe 50 to 70 meters, but because iron formation is so resistant, they’re steep and narrow. While this might sound like the slot canyons of the American Southwest, the gorges differ in several ways. First, there’s so much iron in the rocks that everything is stained various shades of red, orange, and steel-blue. Pretty. Second, the iron formation breaks out into meter-scale beds, so the sides of the Gorges have a pleasant layered look. The softer layers form benches covered by spinifex, gum trees, and a rare type of endemic pine, to name a few plants. Their yellows and greens offset the color of the cliffs. Third, the thin bedding also makes for abundant hand and foot holds when climbing. Fourth, most of the gorges are wet. I don’t know where the source springs are, but all the main tourist gorges have pools, intermittent streams, and waterfalls. Pretty pretty. Finally, given the water, there are lots of eucalypts and other acacias along the gorge floors. Not a cholla in site.

We descended into a side gorge. This was the first place I ever saw iron formation in the raw, so to speak. The steel ladder on the trail - bolted to the rock - was still there, and still a necessary part of descent. Wow, there was a lot of water in the gorge. I pulled out the camera and tripod and got to work. It was overcast, so the contrast was fair, the light a little bland. It’s so hard to be in a place and observe it as needed to take good pictures. Emotionally, I needed both states of mind. I generally caved in to picture taking. This made me sad. The time here goes so fast, hard to savor it enough.

I slowly made my way to Circular Pool, a large waterfall splash pool. By the time I got there, Louis and a bunch of twentysomething Europeans were already swimming in it. I declined the invite to join in favor of photography. Big boulders, seeps with ferns (wow), and the gorgeous iron formation bedding.

The trail weaved upstream through the main part of Dales Gorge. So many images popped in front of me. I ended up carrying my camera attached to folded tripod, which was attached to me via its neck strap. Quicker than setting it up fresh at every opportunity. The brush was thick. The air felt vaguely tropical. I don’t like this landscape as well as the open bush. It is pretty in its own way, but open space and abundant rocks make me more at ease. Harder for me to see pictures in this. We found the impact layer; I made Louis search for the spherules in it.

Finally, I heard rushing water. We came around a bend, and reached Fortescue Falls. This is a cascade more than a waterfall, with a great pool at the bottom. It was definitely time for a swim. I put my gear down. I removed my crusty field clothes (I was wearing swim trunks, no fear). I climbed to the jump off point. I tried to encourage the Swiss girl in a bikini to go in too. Her boyfriend would not pay me to give her a push, oh well. I jumped. Ah, colder than expected. I swam. I got cold, and climbed out. I was refreshed, but still dirty. Maybe it was the multiple laminae of sunscreen and dirt. The Swiss girl finally jumped in. She screamed.

We climbed out of Dales and took a rim trail back to the Cruiser. It was only 11:30. I’d already shot a couple hundred pictures, walked five or six kilometers, and had a swim. Time for a sandwich and escape from Karijini. I wanted to get back toward Newman before night fall. Louis was booked for the BHP Billiton mine tour in the morning.

There was still time to work. For years I’ve had mild lust to get to Mt. Windell, a peak just east of Karijini. I’d seen the rock section on its northern face for years. Good chance the spherule layer would be exposed there. I spied a track heading off the bitumen in the right direction. Hmm, it degraded quickly. I was happy for Louis to see a really bad Pilbara road. So many of the tracks we’d taken were easy, courtesy of all the ore exploration going on. The grass grew fender high. We drove through a two meter wide spider web. I couldn’t see the track. Branches scraped both sides of the Cruiser. The track turned parallel to the bitumen. Bugger. Not enough time to park and hike over to the outcrop. I’ll save Mt. Windell for a future visit.

My second area of interest was the mythical missing spherule layer. I was tired. I was drained from bad night’s sleep, the morning hike, and a cold swim. I was also weary from ten days of intense work (geology and photography). Driving the Cruiser for too long on too many bumpy dirt tracks had dulled my edge. Sometimes the Hamersley Range is too big.

We got to the turnoff. More bumpy dirt. At least it was a track I knew. We parked. I had to sit in the truck for a minute to collect myself and try to focus. I figured the odds of finding the layer were low. The weather had degraded; oh brother, more rain clouds to the west. Anticipating a quick look and disappointment, I took just my field vest and hammer. To heck with the camera, water, and hat.

It’s hard to search in this limestone. I don’t know the rocks that well. They often look monotonous, especially when I lack motivation. This section was badly faulted and folded. I picked a drainage that looked like it had maximum depth of exposure. I dispatched Louis up the east side. I took the west.

I wanted to sit and zone out. I was tired of spinifex and loose rocks. My back hurt. The outcrop was chopped by folds. Pretty rocks though, nice ribbon like beds of tan and brown, reflecting differing iron abundances. I bashed at suspicious looking layers. They were all carbonate. This was annoying. I kicked a rock down the hill. I thought, I should keep going, at minimum I’m a role model. Another two meters of ribbon beds. I grabbed a dead cordwood tree and pulled myself up on a ledge. I looked down.

There it was. I thought to myself, no, it can’t be this easy. I pried a piece off the outcrop. I can’t repeat what I said next in a public forum. There they were. The little bed was pure spherules. Unbelievably, I’d found the damn thing. The rain began.

Fatigue, what fatigue? I yelled for Louis to come over. I traced the bed laterally. It ran about six meters before disappearing under debris and travertine. The rain let up a bit. What to do? It would be dusk in one hour. More rain was imminent. We had to be on the bitumen before either of these conditions occurred. Louis arrived. Crap, I didn’t bring my camera: we used his. So much for being a role model. Where the hell were we in the section? I measured a quick stratigraphic column up to a known marker layer. That took thirty minutes. As we finished, a giant red kangaroo jumped out from behind some brush. He looked at us. I chased him towards Louis, who had enough time to get his camera out. Twenty four years, and finally, a cooperative roo and a good camera.

Back to the layer. Did it change laterally or stay the same? I traced it; no change. What was the rock above and below it like? I needed spherule samples, and lots of them, quickly. I sent Louis to trace the bed around the hill. I found a good spot, and went at the outcrop with my hammer. The wind picked up; it looked wet to the west. Dolomite is tough. I spent twenty minutes quarrying away the beds above and below the layer. In the end, I got about a fist-sized amount of material out. It will be enough to work with.

Time to scoot. I stuffed everything in the pockets of my vest. I almost ran down the hill to the Cruiser. Louis arrived a couple minutes later. I couldn’t see the hills to the west: too much rain. Driving a shade too fast, I got us back to the bitumen.

Where to camp? It was dusk. I was reassured to be on the main road, but it was hard to see tracks that might lead to swag out spots. In any event, where to go, given the rain? We were still several dozen kilometers from Newman. I kept driving. I was tiring, makings it harder to stop. It was almost dark. Finally, a turn off, the old road to Rhodes Ridge. We drove a few kilometers, and pulled off.

I could see rain bands all around us. I’d bought a large tarp in Tom Price. Louis rigged it to the side of the truck as a cooking shelter. It was great, except for the small termite mound that shared the space with us. Oh well, we were too tired to move anything. It was the night for Tastee Bite Indian food and cous cous. I boiled water. We crouched under the tarp and ate. . The wind picked up. It blew an empty pot into my nose. Nice bruise. It finally rained.

Ten minutes later, the rain stopped. What a day. A long hike, lots of photography a swim, a kangaroo, and another spherule layer. I had a lovely swag out under broken clouds. I was happy to see Venus at 5 am.

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