We were ecstatic when we awoke to a gorgeous sunrise, which many of us slept right through after the cold wet day before. We enjoyed a surprisingly orderly breakfast, and made our way to our first outcrop of the day, hoping to learn about the different explosive volcanic deposits.
Quickly moving past a brief stint of vandalism (we ruined a perfectly good lawn finding a place to park), we received a brief lecture from Darren about field observations and sketching. Armed with our measuring tapes, hand lenses, and hyper-fashionable high-visibility orange vests, we explored the mixture of pumice and lithics in the outcrop. Lithics, for those keeping score at home, are small fragments of country rock entrained during eruption. After a few hours of intense study, we came to the conclusion that this interesting mixture of pumice, lithics, and ash was a result of an explosive eruption. due to the consistent wavy layering and organization of the grains of the outcrop. In particular, we noticed that the layers were each made up of grains roughly laid out from smallest on bottom to largest on top, called “reverse grading”. We headed back to the vans to make our way to our way to our second outcrop (and more importantly, lunch).
Quickly moving past a brief stint of vandalism (we ruined a perfectly good lawn finding a place to park), we received a brief lecture from Darren about field observations and sketching. Armed with our measuring tapes, hand lenses, and hyper-fashionable high-visibility orange vests, we explored the mixture of pumice and lithics in the outcrop. Lithics, for those keeping score at home, are small fragments of country rock entrained during eruption. After a few hours of intense study, we came to the conclusion that this interesting mixture of pumice, lithics, and ash was a result of an explosive eruption. due to the consistent wavy layering and organization of the grains of the outcrop. In particular, we noticed that the layers were each made up of grains roughly laid out from smallest on bottom to largest on top, called “reverse grading”. We headed back to the vans to make our way to our way to our second outcrop (and more importantly, lunch).
Upon returning to our van (and the all-important “Soob”), we found an unexpected surprise. A friendly Kiwi had left our entire gang homemade fudge, since we looked to be “up to good”. Although we all knew better than to take candy from strangers, Lydia was kind enough to be our Guinea pig and try some (well before any of us knew it existed). We drove across the graben we observed on Day 2 to our next outcrop, stopping for lunch by a delightful beachside park.
At our next stop, we spent some time sketching the outcrop, a massive wall of flow-deposit with up to 20 cm protrusions of pumice. The flow was set atop an ambitious hill with waist-high grass concealing a generous scattering of large branches. After trekking to the base of the flow and loosening some samples with our hammers (and, for our more creative members, pinecones), we discovered that alongside the large pumice clasts, there were smaller clasts of obsidian and more lithics. This led us to conclude that this was a single layer of poorly sorted volcanic material, deposited as a pyroclastic flow.
One Olympic feat of hill-climbing from Guil to beat our ten second camera timer gave us a spectacular group photo, and one lecture on the formation of felsic obsidian gave us an appreciation for the complexities of the outcrop.
At our next stop, we spent some time sketching the outcrop, a massive wall of flow-deposit with up to 20 cm protrusions of pumice. The flow was set atop an ambitious hill with waist-high grass concealing a generous scattering of large branches. After trekking to the base of the flow and loosening some samples with our hammers (and, for our more creative members, pinecones), we discovered that alongside the large pumice clasts, there were smaller clasts of obsidian and more lithics. This led us to conclude that this was a single layer of poorly sorted volcanic material, deposited as a pyroclastic flow.
One Olympic feat of hill-climbing from Guil to beat our ten second camera timer gave us a spectacular group photo, and one lecture on the formation of felsic obsidian gave us an appreciation for the complexities of the outcrop.
We made our way back to the hotel, where we were distracted by the sunset over the beach as we tried to focus on a paper about volcanic deposits. Even more distracting was the metric-sized paper the article was printed on, but we powered through and synthesized our reading and observations to complete our first graded assignment. We determined the first outcrop was the result of ash falls, while the second was the result of a pyroclastic flow. While we worked, Guil and Lydia cooked a delectable dinner of sausage and mushrooms, before we headed off to bed.
From our beach to yours,
Robby Marshall and Sydney Allen
From our beach to yours,
Robby Marshall and Sydney Allen
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