The last eruption of the Tseax Cone around the years 1750 or 1775 is Canada's worst known geophysical disaster. The eruption produced a long lava flow, destroying the Nisga'a villages and the death of at least 2000 Nisga'a people by volcanic gases and poisonous smoke. The Nass River valley was inundated by the lava flows and contain abundant tree molds and lava tubes. The event coincided with the arrival of the first European explorers to penetrate the uncharted coastal waters of northern British Columbia. Today, the basaltic lava deposits are a draw to tourists and are part of the Nisga'a Memorial Lava Beds Provincial Park.