Semiahmoo Spit is a spit that protrudes from the westernmost expanse of shore on Semiahmoo Peninsula between Semiahmoo Bay and Drayton Harbor off the coast of Blaine in Whatcom County, Washington state. The spit is home to Semiahmoo Park.
https://github.com/davepinch/pinchy.cc/blob/master/content/topics/places/spits/semiahmoo-spit/wikipedia/en.wikipedia.org.md
The mountain is composed of Shuksan greenschist, oceanic basalt that was metamorphosed when the Easton terrane collided with the west coast of North America, approximately 120 million years ago. The mountain is an eroded remnant of a thrust plate formed by the Easton collision.