Castle Rock (volcano)

Castle Rock is a volcanic plug located on Unalaska Island in the Aleutian Islands of Alaska, United States. It is situated near the city of Unalaska/Dutch Harbor. Formed during the Pleistocene epoch, Castle Rock is a prominent landmark composed of solidified lava that once filled the conduit of a now-extinct volcano. Its resistant nature has allowed it to endure erosion that has worn away the surrounding softer volcanic material, leaving it standing as a distinctive, steep-sided rock formation. While not currently monitored for volcanic activity, its existence provides insights into the geological history and past volcanism of the Aleutian arc. The area around Castle Rock is of interest for geological study and is often visited for its scenic beauty and historical significance related to the Aleutian Islands.