Some days of geology field work feel like a vacation – today was not one of those days. “Monsoon” is perhaps more accurate. Our day began before dawn in order to pack and have one final breakfast in Rotorua. We packed into the van, rain gear at the ready, to pick up our newest member, Tom Garden, a graduate student at University of Canterbury. With Tom on board, it was a quick drive to our first stop at the Wairakei Power Station, a geothermal power plant. Tom walked us through the basics of power generation, with wells being used to extract steam and brine in order to power turbines and generate electricity. Overall New Zealand has ten geothermal systems, providing 15% of the total electricity consumed in the nation.
With Tom introduced, it was time to get to work on the first outcrop of the day. Once again donning our fashionable high-vis vests, we observed a roadside outcrop. After two hours of observations using the STC method (structure, texture, composition) and soaking through and through, we found evidence of multiple volcanic eruptions, based on the many distinctly different layers visible. We differentiated these using sorting and grading to distinguish between falls and flows, and the presence of laminates to distinguish the depositional processes. With these observations, we theorized on how multiple eruptions could have created this specific outcrop, as the composition and creation of the layers could suggest their grouping as separate eruptions.
A welcome break in the weather prompted a well-deserved lunch along the shore of Lake Taupo, New Zealand’s largest lake. A quick stop for groceries later found us at a scenic overlook of the lake for a group photo. The view was paired with a quick discussion of the formation of the lake in the caldera, formed as part of the Oruanui eruption, the most recent super-eruption 26.5 thousand years ago.
We found our second and final outcrop of the day on our way up the slopes of Mount Ruapehu, where we are spending the next few days. This outcrop showed another excellent example of a flow, although this time one affected by its interaction with a lake during eruption. We also saw another example of the strange sedimentary deposit we found at outcrop one, which we’ve been kept waiting to learn about for another day. We think it might be the result of water interacting with volcanic material to form a high-energy deposit capable of eroding and cutting through existing layers, and depositing new sediments… but we aren’t sure yet!
We arrived at our lodging, but our work from the day was far from finished. First, we had to carry our bags up the steep, rocky slope to our home, a small rustic ski lodge. In the quick turnaround before dinner, we broke out our soggy field journals to begin our interpretations of the day. A delicious dinner at the Skotel found us well-rested and ready to finish our work and wind down the day.
Huddled by the hearth,
Robby and Reid
With Tom introduced, it was time to get to work on the first outcrop of the day. Once again donning our fashionable high-vis vests, we observed a roadside outcrop. After two hours of observations using the STC method (structure, texture, composition) and soaking through and through, we found evidence of multiple volcanic eruptions, based on the many distinctly different layers visible. We differentiated these using sorting and grading to distinguish between falls and flows, and the presence of laminates to distinguish the depositional processes. With these observations, we theorized on how multiple eruptions could have created this specific outcrop, as the composition and creation of the layers could suggest their grouping as separate eruptions.
A welcome break in the weather prompted a well-deserved lunch along the shore of Lake Taupo, New Zealand’s largest lake. A quick stop for groceries later found us at a scenic overlook of the lake for a group photo. The view was paired with a quick discussion of the formation of the lake in the caldera, formed as part of the Oruanui eruption, the most recent super-eruption 26.5 thousand years ago.
We found our second and final outcrop of the day on our way up the slopes of Mount Ruapehu, where we are spending the next few days. This outcrop showed another excellent example of a flow, although this time one affected by its interaction with a lake during eruption. We also saw another example of the strange sedimentary deposit we found at outcrop one, which we’ve been kept waiting to learn about for another day. We think it might be the result of water interacting with volcanic material to form a high-energy deposit capable of eroding and cutting through existing layers, and depositing new sediments… but we aren’t sure yet!
We arrived at our lodging, but our work from the day was far from finished. First, we had to carry our bags up the steep, rocky slope to our home, a small rustic ski lodge. In the quick turnaround before dinner, we broke out our soggy field journals to begin our interpretations of the day. A delicious dinner at the Skotel found us well-rested and ready to finish our work and wind down the day.
Huddled by the hearth,
Robby and Reid
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