6/26. Another predawn stroll. When I returned more of the camp was awake. To avoid the crowd we again tossed all of our stuff in the Pajero and set off for the east side of the Bungle Bungle. This is the famous part: the so-called “Beehives”. OK, I should get all geological at this point. The Bungle Bungle is a large mass of sedimentary rock; conglomerate to the east, fining to sandstone on the west side. It’s the detritus shed from a mountain range that once existed to the west. Too bad it’s not full of gold like the Witwatersrand in South Africa (a similar tectonic setting, albeit much younger). Through some combination of lithology, geologic structure, climate, time, and fate, the sandstones have eroded into truly fanciful dome shapes - the Beehives. I can’t stand to use this name; I’ll stick with the generic of “domes”. The domes are steep-sided, and grouped into fins that run out from the edge of the Bungle Bungle massif. I called these features sandstone karst in an earlier post, based on my pre-trip research. Having seen it, I think it’s a unique expression of mechanical weathering – the rock breaking into pieces- which is totally different than the chemical dissolution of karst formation.
No matter. The Bungle Bungle domes are most striking for being banded: alternating layers of black and orange/grey bedding. OK, I’ll be geological again. What’s the banding all about? On fresh surfaces, the Bungle Bungle sandstone is grayish-white, as it should be, since it’s composed mostly of quartz sand. However, like everything else in Outback Australia, on weathered surfaces the rock is stained orange-red; i.e., it’s rusted. What makes the Bungle Bungle different is that about half of the beds are covered by a thin layer of cyanobacteria, making them black. To my eye, the black bands were slightly coarser grained strata; maybe water percolates through them easier, making the bacteria happier? The bands are around a meter or two thick, so the domes are most aesthetic from a distance. When you see them, you just have to go, wow.
Breakfast at the car park, at the very margin of the domes area. I ate and stared at the hundreds of individual domes, each a unique shape, forming what passed for a cliff face. En mass, the domes gave me a perception of motion, almost like they were flowing downhill. Finally being this close to them, the domes were surprisingly hard to comprehend. Some of this was truncated perspective; the trees and shrubs around the car park cut off the bases of the domes. In addition, although I knew the scale of the domes from my reading, I could not perceive this when looking at them. Strange – maybe the final remnants of jet lag.
We looked forward to completing a few short hikes in this area. Unfortunately, so did almost every tour group in Purnululu. To get away and avoid feeling rushed, we headed off trail down Piccaninny Creek. This is the main drainage on this side of the Bungle Bungle. We followed it out to the edge of the range. Needless to say, it was hot. It was interesting to wander up close to a few domes. The bands, regardless of color, were given a variety of textures the sedimentary bedding in the sandstone. At arm’s length, this comprised a beautiful suite of fluvial features; cross-beds of various sizes, concave erosional channels that truncated older layers, accretionary sand bar sequences. Once my analytic brain had perceived this, I let go of this part of the experience, and just tried to take pictures and see the domes through my other eyes.
This aspiration was successful until I started looking at the creek bed, which was quite interesting. It was filled with rounded gravel and boulders; most of the sand eroded from the domes was somewhere far downstream. Convincing evidence of high velocity stream transport during the Wet. In places where the bedrock was exposed, it was scoured into potholes and long runnels. While this is not uncommon in bedrock channels, I was awed to find the very deepest potholes in the top of a sort of ridge in the middle of the stream. Only high stream flow would do that!
We found some shade and dozed. The sun got higher; the shade ebbed. I heard voices. Oops, we had been poking around in full view of the lookout point. Well, all those tour groups now had a scale in their photographs.
Eventually, it was time to walk again, so we followed the tour groups up Cathedral Gorge. Another narrow chasm, with remnant pools at its lowest points; somewhere else not to be in the Wet. We’d heard one tour guide asking if anyone in his group could sing. Another narrow chasm like Echidna or Mini Palm. The trail turned, and suddenly opened up: the Cathedral, a large semicircular cavity, at least 100 meters across. A large pool filled the center of its sandy floor. We sat on the edge, and both admired the Cathedral and cooled off; it was nearly noon. No one sang. A trio of little girls, clearly sisters, ran about and played. Seeing their unrestrained joy made me happy to be here.
After enduring the afternoon heat, we returned to our breakfast spot for dinner. I was looking forward to some moonlight photography. My tripod was ready, I had a view picked out, and suddenly, it got darker. A partial lunar eclipse. I adjusted for a longer exposure time.
6/27: We’d seen Purnululu from the ground; it was pretty world heritage-esque. Like many notable parks, a view from the air was also available. I’ve avoided supporting such concessionaires since my days at the Grand Canyon, where one of my tasks was to measure noise pollution caused by tourist overflights and the occasional military jet. However, much of the Bungle Bungle is not accessible. It’s either roadless or proscribed by the Aboriginal bands who legally own much of the land. In addition, the helipad was ten minutes from our campground.
At 7 am I thus found myself listening to a five minute safety lecture, “exit the helicopter to the front, please avoid the expensive whirly bit at the back” and “you may have nothing, absolutely nothing, in your pockets, which might get sucked out (the helicopter was doorless) interact negatively with the expensive whirly bit on top”. Once briefed, we boarded a Robinson 440 with our pilot Danny and were off on a thirty minute cruise over the Bungle Bungle. It was the first flight of the day; pleasantly cool at a couple thousand feet.
The flight was genuinely fantastic. It was eighty minutes after dawn, so the light was still pretty good. To see the domes from the air and dive into amphitheatres and chasms that I could never hike into was awesome. The domes were less mysterious from above. I could see the structural control (largely jointing) on their formation, which let me map them into my geologic frame of reference. Danny was a fun and an indulgent pilot. He happily abandoned his usual spiel when he found out I was geologist, and asked me questions that I could mostly answer. I figured out how to take pictures with one hand – a bit trick given the g-forces in a helicopter with open doors - and hold the intercom button down with the other so we could chat. He dropped the Robinson a bit lower than normal to give us good views of a couple spots.
In addition to the scenic aspects of the flight that we were supposed to enjoy, flying in helicopter is always a kick, especially the way the machine simply lifts off the ground. I was having too much fun shooting pictures and chatting to worry about hanging out of the door on some of our steep banks. A good way to finish time in the Bungle Bungle.
So it was time to leave the first place. We did a pretty good job seeing the available parts of the park, in all the ways in could be seen. An acceptable reintroduction to Australia, and a good way to meet the East Kimberley. The visit was a blur in the ways that visiting a new place is always superficial. So much newness that it is hard to feel the depth of a place.
No comments:
Post a Comment