A Coronation Sill "sliding" into the Arctic Ocean. This bay of rampants to the east of Kugluktuk is just one of dozens of parallel sills slicing through Nunavut's western mainland, each and every one with the same shallow dip to the north. They form a series of ramparts on land and many linear sets of islands out in the ocean.

These distinctive intrusives in the form of sills are the result of a large-scale igneous event 723 million years ago. The rocks they cut through are anywhere from a half billion to one billion years older. Which means older rocks on both sides (above and below) were separated by the sill. Relentless erosion with a final polish by recent continental glaciation has uncapped and dessicted this one.