For the most recent bout of fieldwork I set my sights on the Kaipo Valley, a seldom-visited valley north of Milford Sound. Despite enormous slips with copious outcrop, the last visit by geologists was in 1998 and before that in the 80s. Descriptions of the geology were few and varied so we did not know what to expect. The flight in (via a 50 year old Cessna) was nice and bouncy due to strong winds which had our stomachs dropping and the look on the pilot's face told us we might be turning around. Once out of Milford Sound, the winds were not so bad and we followed the fault straight to the Kaipo Valley. To drop altitude the pilot flew further up the valley where it narrows. I got a fantastic 3 second view of the mile-high Kaipo Wall, before a full sideways turn the width of the valley set us on a flight path for the swampy airstrip.Still having a half day of pristine weather, we set up a carefully selected camp and headed out into the field in search of the Alpine Fault. Examining rocks in the creek bed, I realized a good portion of the rocks were wholly new to me- a frequent frustration in this complex field area of mine. In particular, the igneous and metamorphic textures were some of the most spectacular I have seen anywhere in New Zealand. I satisfied myself with taking pictures rather than comprehending their full significance. Luckily the outcrops along the fault tie into the fieldwork I did in the Hollyford reasonably well, so I had some confidence in the geology we were looking at. We ended the day right at sunset. In the evening we met the hunters staying in the Kaipo Hut. A good, friendly sort, we probably would not have to worry about being shot.
Welcome to the Kaipo Valley
Kaipo Camp
Day 2 we continued up the creek following the Alpine Fault, spending time taking more detailed observations and samples. My field assistants did a great job gardening, and were able to expose several useful outcrops. This creek, although steep and slippery, made for easy travel compared to a lot of the creeks in my field area. I collected some samples of some rainbow-colored gouge that will hopefully yield useful friction results. It was another glorious day for fieldwork.
Proud gardeners
Rainbow sherbet fault gouge
Day 3 I awoke to frozen boots and a thin film of frost on everything in sight. Despite brain-numbing temperatures, we marched across the foggy bog towards the Kaipo River, in hindsight taking probably the most horrible route possible. We then headed up the Kaipo in search of the enigmatic Pembroke Fault, an apparently major fault about which little is known. My feet warmed up from near-hypothermic to normal just in time to cross some small creeks and begin the process again. Above the river flats the Kaipo is a rather steep and uncrossable river dominated by rapids, deep pools and large boulders. We fortuitously found a 15m long log perched perfectly across the river- exciting, novel and much safer than the alternative. We had lunch at the best spot on the river (complete with blue duck cruising past) before descending into the dark, dreary and heavily-vegetated creek where we hoped to find outcrops of the Pembroke Fault. This was grim and we turned around with not much to show for our effort. Some creeks just do not have outcrop and this was one of them. We got back slightly earlier than previous days but it is still amazing how long it can take to go a few kilometers in terrain like this!
The miraculous Kaipo log bridge
5 star lunch spot, 1 star geology
The last half day was spent examining the rocks in the main Kaipo Slip to compare to previous descriptions and to tie it to the observations we made in the creek nearby. What an impressive slip! It is really about 20 slips making up one giant amphitheater almost a kilometer wide. We spent several productive hours in awe of the complexity of the geology. It gave me much to think about. Shaun picked us up a bit early and whisked us off on a spectacular scenic flight back to Milford via the head of the John O'Groats, the Transit and Lake Ronald.
In the end I feel like I have a much better understanding of the geology in northern Fiordland and a whole new view of this part of the Alpine Fault. Hopefully the samples will yield similarly interesting results.
Miss Kaipo Valley
Alpine Fault in the John O'Groats
Thanks to Shaun Ferris of Fly Fiordland for getting us in and out and showing us a good time along the way. Thanks to National Geographic for funding. Huge thanks to my great field assistants Marco and Zoe.
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