Thursday, June 8, 2023

Guest Blog post by Ross Ellingwood coming in on S/V Bluemoon hailing from Whittier, Ak.

Sailing in last night I got my first glimpse of Seguin Island and the state of Maine at that. It was a beautifully calm evening with high clouds and patchy blue sky. Passing in-between Ellingwood Rocks and the island, a humpback whale greeted me as he came to the surface for a breath. What a welcome to Seguin!

After taking a mooring ball and rowing to shore I quickly started noticing some very interesting rocks. Having a background in geology I immediately noticed large streaks of vertical white looking rock from the water. Under closer inspection these turned out to be intrusions of granitic rock. This is caused by hotter molten rock from deep down finding cracks and weaknesses that it’s able to push up through. The white and pink hued granitic rock against the dark bedrock makes for an easy spot. 

The dark bedrock that makes up the majority of Seguin Island seems to be a metamorphic rock of varying grades. Metamorphic rocks are sedimentary or igneous rocks that have been altered by high pressures and heat to change their composition over time. The more heat and pressure, the more alteration, the higher the grade of metamorphic rock. Along the North Trail the rocks seem to be a phyllite or schist, a medium to high grade metamorphic rock. Near the Cobblestone Beach Trail there looks to be Gneiss which is a higher grade. Gneiss can be spotted from its characteristic wavy bands. Also near Cobblestone Beach a large quartz vein can be seen cutting through the bedrock. 

This is a very special place not only because of the rocks but the very friendly Lightkeepers Lee and Rick. They were very gracious hosts showing me the lighthouse and explaining the history. I am very glad I decided to make this my first stop in Maine! 

Ross Ellingwood with his boat Bluemoon and Ellingwood Rock (no relation) in background.
Gneiss rock sample near Cobblestone Beach.

1 thought on “Guest Post: A Geological Peek at Seguin

  1. Thanks for your post Ross! Great to meet you. Serendipitous mooring time with John and Deb too!

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