With its myriad islands, Alaska has nearly 34,000 miles (54,720 km) of tidal shoreline. The Aleutian Islands chain extends west from the southern tip of the Alaska Peninsula. Many active volcanoes are found in the Aleutians and in coastal regions. Unimak Island, for example, is home to Mount Shishaldin, which is an occasionally smoldering volcano that rises to 10,000 feet (3,048 m) above the North Pacific. It is the most perfect volcanic cone on Earth, even more symmetrical than Japan's Mount Fuji. The chain of volcanoes extends to Mount Spurr, west of Anchorage on the mainland. Geologists have identified Alaska as part of Wrangellia, a large region consisting of multiple states and Canadian provinces in the Pacific Northwest, which is actively undergoing continent building.
What do geoligists believe isn't unique about Wrangellia?