Wrangell is the only volcano in the Wrangell Volcanic Field to have had historically recorded eruptions, generally in the form of small steam and ash explosions. Reports of activity have been recorded in 1784 and 1884-85. The 1784 eruption and another stated to have occurred in 1760 are disputed. The 1884-85 eruption was reported by local prospector Jon Bremner. An 1890 report mention a visible glow. Wrangell also occasionally emits ash, which can be seen coating the summit snow. The bulk of the mountain was built by large lava flows from 600,000 to 200,000 years ago. The summit caldera is believed to have collapsed within the last 200,000 years, and may have collapsed 50,000 years ago. Mount Zanetti is about 25,000 years old.