Once upon a time, there were three pillow quarries

June 29th, 2009

Ben Edwards arrived from the States today. After a short morning of getting acclimated, he and the Wooster crew headed out to the field with our Icelandic colleagues, Steina and Hauker. We visited 3 quarries that expose the internal architecture of 2 different pillow ridges. Pillow ridges form during subglacial eruptions, where the the ice melts and the lava is quenched. Thanks to the heavy machinery, we are able to see natural cross sections of the ridges, and we’re observing a lot of unexpected details. Most quarries show nicely preserved pillows, with radial cross sections and glassy rinds. Vesicles appear in a variety of patterns, sometimes concentrated in the center of the pillow or in concentric zones around the center. Surprisingly, there are a lot of intrusions as well. We observed one of the best examples of a feeder dike in contact with its lava flow. There were also some irregular and sheet-like intrusions that stood out against the wall of pillows. Clearly, there are a lot of questions to be answered here. Todd is going to address some of those questions in his I.S.

Adam using a hand lens to identify phenocrysts.

Adam using a hand lens to identify phenocrysts.

Pillow lavas with a hammer for scale. Notice the radial joints. The pillows are surrounded by brown, altered glass.

Pillow lavas with a hammer for scale. Notice the radial joints. The pillows are surrounded by brown, altered glass.

A light gray dike intrudes through black, glassy, brecciated material and feeds an upper unit of gray pillows.

Todd (on the right) is pointing to a light gray dike that intrudes through black, glassy, brecciated material and feeds an upper unit of gray pillows.

Iceland: The Beginning

June 28th, 2009

We made it to Iceland! We landed Friday morning and have been busy having fun (and seeing great geology). Our chefs have been cooking excellent meals.

Adam, Rob, and Todd eating their awesome salmon dinner on the first night.

Adam, Rob, and Todd eating their awesome salmon dinner on the first night.

All of the food has been fantastic, especially the cheese. Todd likes it so much, he bought a whole block of it for himself! Rob and Todd have eaten fish for every meal and plan to continue for the entire trip.

As soon as we landed, we traveled along the southern coast to meet a group of geologists on a field trip. We’ve seen glorious columnar joints, complicated intermingled granophyre and basalt, and highly altered hyaloclastite. We also ventured all over a glacier, where we drank some melt water and stood in a glacial cave.

Todd, Rob, and Adam standing in a glacial cave.

Todd, Rob, and Adam standing in a glacial cave.

At one stop, we walked along a black sand beach. Well, most of us did.

Adam taking a snooze.

Adam taking a snooze.

Todd and Rob made rock sculptures and signed the sand.

Todd and Rob on the black sand beach.

Todd and Rob on the black sand beach.

Just down the road, we visited the Dyrholaey bird sanctuary. The basaltic lavas and hyaloclastites have been carved into interesting shapes by the crashing waves.

Todd, Rob, and Adam on a VERY stable rock bridge.

Todd, Rob, and Adam on a VERY stable rock bridge.

Hyaloclastites are glassy fractured rocks formed when lava erupts explosively in water. One of us attempted to find the source of the lava…in the COLD Atlantic ocean.

Rob (in the red trunks) searches for the lava source while his comrades (lower right corner) observed his methods.

Rob (in the red trunks) searches for the lava source while his comrades (lower right corner) observed his methods and took notes. They concluded that they should not follow.

In Hveragerdi, we observed the effects of the hotspot in action. We hiked along a trail that had fumaroles, hot springs, and mud pots. The local stream is heated by drainage from the hot springs and serves as a natural hot tub.

Todd and Rob soaking in an Icelandic stream.

Todd and Rob soaking in an Icelandic stream.

We’re in Hafnarfjordur tonight, staying with Steina, one of our Icelandic colleagues. Tomorrow starts our field work – we’re headed to Todd’s site: Undirhlithar.

Fieldwork Audio Post

May 20th, 2009

Speaking of fieldwork, check out my audio podcast on a typical day of fieldwork in Iceland. I learned how to make this (and do a lot of other neat stuff) in the Instructional Technology Fellows Workshop.

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