Rocks found on the island are volcanic, and the island is characterized by its "precipitous cliffs". A "Pecten conglomerate" from the late Pliocene or early Pleistocene period has been identified on the island, situated on a wave-cut platform at 720–820 ft. The island is a rare volcano type called a tuya, or moberg, which was formed by a three-stage eruption sequence below an ice cap.
The island's volcanic origin is evident in its rocky composition and dramatic cliff formations. A specific geological formation called a Pecten conglomerate, dating back to the late Pliocene or early Pleistocene period, has been discovered on the island. The island itself is unique as it is classified as a tuya or moberg, a type of volcano formed by a series of eruptions beneath an ice cap.