Thursday, December 20, 2012

Paleomag on the Crescent Formation

I have been going through old film pictures. I still believe one of the greatest technical advances for geology is the digital camera. 

When trying to coax a story out of rocks some geologists do more than simply look at the rocks and whack them with a hammer. Here Andrew Warnock cores some Crescent Basalt on the Olympic Peninsula. If I recall we gave Andrew a tough time as he was coring the rock.

After cutting a rock core with the drill, Andrew marked the horizontal line and angle of the core and then took the core to the lab where he measured the paleomagnetic signature of the rock. As the lava cooled iron bearing minerals aligned slightly with the Earth's magnetic field leaving a magnetic signature in the rock.  Andrew drilled dozens of cores and measured dozens of magnetic signatures in the Crescent Formation. Using that data he could unfold and realign the basalt to its original position contributing to our understanding of the Crescent Formation.  What latitude was the lava when it first flowed on to the surface? How has it been moved since that time?

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