What was the name of the Chilean volcano that Darwin witnessed erupting in 1835?

The Chilean volcano Darwin witnessed erupting in 1835 was Mount Osorno. On 19 January 1835, during the second voyage of HMS Beagle, Darwin was near Ancud in southern Chile when he observed the volcano’s eruption.

Osorno is a prominent, snow-capped stratovolcano in the southern Andes, rising beside Lake Llanquihue and near Lake Todos los Santos. Darwin recorded the event in his journal and connected it with reports of earthquakes and volcanic activity elsewhere in the region. The observation helped him consider whether volcanoes separated by great distances might be linked through deeper geological processes.

The date matters because Darwin’s Chilean observations occurred during a particularly active period. The great Concepción earthquake of 1835, which Darwin experienced earlier that year, also shaped his geological thinking about uplift, seismic forces, and the changing surface of Earth.

Mount Osorno is sometimes confused with Ecuador’s Cotopaxi, Aconcagua on the Argentina–Chile border, or Chimborazo in Ecuador. Those are all major Andean peaks, but Osorno is the volcano specifically associated with Darwin’s witnessed Chilean eruption.