Local Techtonic Action

Hey guys,

So we all know that this is the Marine ‘BIOLOGY’ Quarter and we are primarily studying living things in marine environments (which is of course the coolest aspect of marine science). However, there are many physical processes occurring in and around the world’s oceans that ultimately affect marine biota. The geophysics of the ocean floor is a major one and as was evident on Sucia Is., we are sitting in a pretty unique geological location.

The islands are the highest points of an underwater mountain range that connects Vancouver Is. to the mainland. They were formed as a result of the Juan de Fuca tectonic plate subducting (forced underneath and melted) underneath the North American plate. Subduction zones can lead to intense volcanic action as the crust of the plate being subducted is liquefied in the upper mantle and forced upwards again.

As Emily briefly explained, the cliffs on Sucia Is. are actually comprised of ancient sea floor sediments that were pushed upward due to geologic activity and eventually carved up by glaciers during the “Wisconsin Glaciation” of the last major ice age. The calcified structures of the fossilized organisms we saw were preserved due to the intense pressure of being buried under constantly forming sea floor sediment layers.

Seeing these ancient fossils on Friday was really cool! I really wish I had brought my camera, I’m jealous of Mike’s awesome pictures. I think geology and paleontology are really cool and again, this is a great area to see it in action. I would like to do some reading on fossils and go back to Sucia sometime in the future.

The trip over on the R/V Centennial was really nice too. I had a good time chilling on the deck and in the cabin and filling out dichotomous surveys. Kevin’s algae lecture was pretty cool. I’m definitely looking forward to seeing all those species on our dives.

This was actually my third experience doing an otter trawl and second doing one on the Centennial. I got to spend the night at FHL last winter for my BIOL 180 field trip and we did one then too. My first was with Tim Essington for FISH 210. Otter trawls are always awesome. Even though I kind of feel bad that so many of the animals suffered pressure trauma. Oh well.

Our first week here has been really great! I can’t believe how much we’ve done so far. I’m really looking forward to the rest of the quarter!

Also, here is a really informative (and cool) publication put out by UW geologists. Hence the title, it explains the many geological features of the San Juan archipelago and how they came to be. Check it out!


-Sean Luis


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