Cascade Fieldwork June 1-3

Off to the Cascade, Marytr and Jackson Rivers for a few days of solo fieldwork before a drive up the coast to meet up with the cavers. This is the area I have spent the most time and since fieldwork is now starting to wrap up, it was easy to drift into nostalgia.

When I arrived there was abundant evidence of recent rains and the bush was still thoroughly wet (and thus me too as I waded through it). The days were short and cold, but at least were sunny and (relatively) sandfly-free. Doing fieldwork alone, I often worked late days, arriving back at my car an hour after the sun had set.

This fieldwork was a bit unusual for me in that it was not exploratory "map and see" fieldwork, but a very focused trip to grab very specific samples for laboratory tests that I wished to do. Finding these samples could take a couple hours or a lifetime...

I stopped at the Marytr River to collect calcite from both sides of the Alpine Fault (by comparing stable isotopes in them I can maybe tell whether both sides are hydrologically connected or separate like California's San Andreas Fault). I did reasonably well and found good samples that should be suitable. As a side note, the Marytr outcrop appears to be rapidly evolving (eroding) yet again!


Lower Cascade

I spent a whole day wandering around the giant Cascade rock avalanche making observations and desperately looking for organic matter in the deposit so I can estimate its age. After lots of digging I found a few slimy, organic-looking chunks, which may or may not be sufficient. Fingers especially crossed on this one.


Rock avalanche deposit and Cascade River

I grabbed a mylonite (ductile fault rock) sample with green hornblende crystals from a creek near Martyr Saddle. By dating this mineral, I should be able to determine whether the fault-related deformation can be attributed to the Alpine Fault or is much older.

I also crashed up an unnamed creek just south of the Arawhata in search of the southernmost schist mylonite. Negative. The southernmost schist mylonite is somewhere north of my field area!

It's hard to have good action photos doing fieldwork alone so enjoy the scenery shots!


Jackson River Road