Alpine Fault Fieldwork Mar-Apr

Back to New Zealand for some fieldwork. The main goal was to get my student Jozi going on her PhD work. We had the disadvantage that we had not yet received the data we needed to inform our fieldwork, which made everything a bit of a gamble. Add on some challenging fieldwork and it amounted to the least productive fieldwork I've had overall. Several things were accomplished though and the weather was nice. We just saw more bush and less rocks than usual. 

The first half of fieldwork was Cessna fly-in to Martins Bay, then a short walk to Martins Bay Hut. Then a jetboat ride to Hokuri Creek and a hike up river to establish a camp. We worked several days in the Hokuri area chasing down marine terraces that turned out to be post-glacial lacustrine shorelines- far less useful. When the weather turned sour we based ourselves out of Hokuri Hut and I packrafted to all the McKerrow survey monuments to check their visibility. I also made a desperate attempt up the creek on the far side of the lake. In foul weather and with blistered feet we hiked our heavy packs towards Martins Bay for pickup. Long story short I ended up going solo, arranging a jetboat pickup, then running back to Hokuri Hut for the final night. Huge thanks to the good folks at the Hollyford Track for incredible hospitality in an often hospitable place.

Round two would be some proper West Coast fieldwork, driving over Haast Pass to Jackson River and the familiar camp spot there. We spent an additional couple days collecting cosmogenic and thermochron samples and examining the latest iteration of the Marrtyr River outcrop.

        A cleaned Martyr footwall exposed, Alpine Fault at center

Deep Canyon Mar 7-10

Feeling a little overwhelmed at the office and home I sought out a working holiday doing a little fieldwork and writing at the University of California's Boyd Deep Canyon Reserve. The area has an interesting abundance of very large rock avalanches of unknown ages that I wished to map and sample. The image above shows one of the bouldery surfaces of one of these rock avalanches. The right horizon consists of a smooth dipping detachment fault surface separating felsic plutonic rocks (left skyline) in the hangingwall from the gneissic footwall rocks (right skyline). Interestingly the gneiss rocks only allow shallow drainages to form due to the low rainfall and high strength of the rock creating a shield-like surface. The granitic rocks above form relatively steep slopes that become isolated hills that in the right circumstances can collapse catastrophically sending a fast moving flow of jumbled rocks cascading several miles distance. All the rock avalanche I examined clearly are a delamination of the plutonic rocks on the weak, well oriented detachment fault surface.

An added bonus was a very green desert, complete with a wonderful wildflower display and highly active bugs and hummingbirds. It was a great little getaway.