Tuesday, October 04, 2016

Keem Bay

I like small beaches in spectacular settings with a lot of little geomorphic details. I like beaches that I don't expect. I like it when the sun comes out. I like beaches that you get to by driving a narrow road high above the cliffs and where it's hard to stop to take pictures because there are sheep in the pullouts. I like beaches where we remember to bring the baguette and the brie and where they serve ice cream out of a truck in the parking lot.

Keem Bay is located near the western tip of Achill Island, one ridge and some very high cliffs away from the open Atlantic. The pocket beach is cut into the bottom of a small, steep valley. The bluffs behind the beach consist of rocky soil and glacial drift (I think) which shed all sizes of material, including enormous boulders, onto the beach. The stream that drains the valley cuts a small ravine behind the beach, then spills out across it.

Stones eroded from the bluff are reorganized by storm waves into a steep cobble berm. Heavier minerals are separated from lighter ones as waves wash across the upper beach, leaving thin layers of black sand. Finer sand is blown by the wind to form ripples and streaks across the beach.

Achill Island is built on heavily metamorphosed schists and quartzites associated with the Dalradian Supergroup - apparently Precambrian to early Paleozoic (from the internet, you can't tell by looking at them). There were some cool boulders at the back of the beach - but my metamorphic petrology is far too ancient and deformed to share with anyone else.

No comments: