Toward the beginning of my PhD I won a scholarship from an organization that gives grants to students doing research in the Taranaki region, and as part of the bargain I agreed to come down to New Plymouth in early December to give a public lecture at the Puke Ariki, the city’s big cultural and natural history museum. I decided that while I was down there already I’d take the opportunity to do one last batch of fieldwork before the end of the year.
My co-supervisor at Victoria University of Wellington drove up and met me in Oakura (a small town in the northwest part of the peninsula), and we planned a couple days of exploring and sample collection.
I’ve already told you about looking for stratigraphic sections and learning to tell apart the different types of deposits that I look at during my fieldwork. And about mapping those deposits in different places. Naturally, the next step is to actually take samples of those different deposits to take back to the lab for testing.
I had already done a good bit of sample collection on the last trip (the one forever lost to the annals of my dead hard drive), but there was plenty more to do in the same (and new) places, so off we went back into the park, up the Puniho track, and into Maero Stream.
We started by climbing up toward the “type section” I’ve already told you about, but this time we decided to push on a bit farther and see what lays higher up the stream. The first thing we noticed on the way up was a really red outcrop, different from anything we’d seen so far. Farther on up we also found a potential good spot to get into and out of the riverbed, which might be good to know about for future trips. It would be very convenient to be able to follow the easy track much further along rather than having to climb up the rocky stream bed.
We stopped at the red unit again on the way down to take some samples. What does that mean, exactly? Well, basically, there’s a few different types.
- Matrix and clast samples: Basically, I just scoop a bunch of stuff that I think is well representative of the outcrop into a sandwich baggie. The matrix is the sandy stuff in between the clasts (the pebble to boulder rocks contained in the matrix).
- Oriented core: We use a drill (I’ll show more later) to take a little cylinder, roughly the diameter of a quarter (NZ/Euro 50c coin) and around 4-8 cm (2-4 in) deep.
- Oriented hand sample: When we can’t drill a hole in the field, instead we just take the rock home instead so we can drill a hole in it back in the lab.
- Charcoal: For radiocarbon dating you need stuff with lots of carbon. One thing with lots of carbon are burnt bits of trees, leaves, and twigs.
So notice I used the word “oriented” a few times in the sample names. That’s because for paleomagnetism direction is everything. Later in the lab we’ll be trying to figure out the direction of earth’s ancient magnetic field. But to do that, we need a reference point for the direction of the rock when it was deposited. So we spend a lot of time recording with compasses and marking the rocks with sharpies so we’ll be able to test accurately later on.
Another question you may have is “what if you don’t find any big enough rocks to take as oriented hand samples?” It’s a good question, and this time out we got to test another sampling method, where we hammered a little plastic box into the fine grained material and took an orientation of it (see picture above) in order to get a sample. It will be interesting to see if it works. We also found some little charcoal bits for the first time, which should be helpful.
After some pretty lousy weather on the first day, we got much better conditions on day two. Here, we found some good outcrops right along the road to ample, which meant we could test out our drill. Vroom vroom!
We only tested a couple times, but we drilled two useful cores. Funny thing was, the drill was tough to get started…but then once it got going we couldn’t get it to shut off! A Hanukkah miracle! Eventually we just had to remove all the fuel and let it run itself down.
After finishing fieldwork on the second day, my supervisor took off for home, and I went to do the actual purpose of my trip–the talk at the museum. Basically, I got to do my proposal defense, but slightly longer and for a broader audience. It was quite fun, a good chance to get to talk to people in the area and get their perspectives on the volcano. And of course a great chance to screen Geology: The Movie (provided here for your education and entertainment just in case you haven’t seen it or want to watch again).
When I finished with that, it was time to celebrate. Fancy dinner? Chill on the beach? Nah, how about we climb a volcano instead?
I took a drive around the northeast side of the volcano to a place where you can actually drive a decent ways into the park to the North Egmont Visitor Centre. As I got closer I willed the small bits of clouds that remained in the sky to drift away. “Show yourself, you majestic fucker!” And show himself he did.
From the visitor centre I started off on the summit track. While my field area is on the western side of the volcano, this is probably the easiest route to the top, and I imagine this is the way we go when we get around to doing fieldwork at the summit. For this trip, I wasn’t intending to go all the way up and back, that takes a full day. I just wanted some quality time with just me and Taranaki and to see how far I could get in an hour or so.
The track (as far as I took it) is well paved and easy to follow–that’s not to say it isn’t quite steep and strenuous all the same. And that’s the easy part! I got pretty high up, almost to the bottom of the volcano itself, but it’s quite the climb to get to the top. Still a bit too much snow to do it at the moment, as well, but hopefully I’ll get back there in January or February when things are clearer.
That just left me with a little more fieldwork to do on the final day before driving home, as well as one important pit stop on the way home.
With that, I’m done with fieldwork for the year. After wrapping things up at the office, I’m off on a holiday visit from my parents and a whirlwind tour around both the North and South Islands.
Have a good end of the year everyone, see you in 2016!