Wednesday, May 21, 2014

Geo 730: May 21, Day 507: A Logical Question

Looking across the mouth of the Coquille River to the north jetty, Dana asked a perfectly logical question: "Is it made of blueschist, too?" I had not considered the question before, and I honestly don't know the answer. Given what I can see at that distance- basically color alone- it looks consistent. And certainly, given the circumstances of construction, I'm guessing both jetties were built together. It wouldn't make sense to only have one for some period of years. Since a quarry close to the water was established to supply the stone blocks for the south jetty, it would make sense that the same quarry was used at the same time to supply stone for the north jetty. So I'd be willing to bet a small amount that the north jetty is blueschist, too, but I'm just guessing with logic. I don't really know. I *do* know that people sometimes visit that light house, so that jetty probably isn't too hard to get at... ROAD TRIP!

Photo unmodified. March 9, 2012. FlashEarth location.


Ron Schott said...

Spoiler Alert!

Yes, the north jetty is also made of blueschist blocks - that's where I collected mine years ago.

Lockwood said...

Thanks for letting me know! The first time I went was in structural geo, and Yeats had been hoping to get some metamorphic features to map in the old quarry (now developed as homes and condos- more coming on that), but we found it too fine-grained and chaotic. So we went out to south jetty, and that's just where I've gone ever since out of habit. It looks like less out-of-the-way access, too.