Plenty to do but with a keen field assistant and good weather forecast lined up, I was back to the Coast for some touch-up fieldwork before I start writing up a paper on the Martyr River section of the Alpine Fault. The focus of this trip was to measure and sample some of the previously elusive outcrops that require either a raft or rappel to access. Carrying an inflatable raft through the bush to the river certainly had its novelty. We rigged an anchor upstream of the pool so that I could be kept stationary against the cliff rather than at the mercy of the current. My humble research vessel, Martyr I, functioned surprisingly well and I was able to document a continuous 30m section through the Alpine Fault footwall. I was also able to row across to check another outcrop.The river has changed greatly since the 10yr Southland flood of a month ago. Many of the easy crossings were gone, new rapids appeared, and pools moved. One of the planned rafting traverses now had a rapid at its head and was abandoned. Also some serious looks at the big slip outcrop persuaded me not to rappel down it again. I still had too many fresh memories of cascading rocks from a year ago and the slip did not look any more stable.
I also spent some time documenting the latest incarnation of the Martyr Alpine Fault exposure and rappelled down waterfalls to get a good sampling transect. I found a new outcrop a stone's throw from the road in a Jackson tributary, beautifully exposing the abrupt transition from footwall mylonites to Greenland Group gneisses. The evenings had an unnatural amount of moisture in the air, which despite the fine (but cold) weather, thoroughly soaked everything. Photos by Lara. Thanks to her.
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