Azores

Sao Miguel - Geological Highlights

Given the water abundance on Sao Miguel, interaction between water and magma is very probable. When such phreatomagmatic eruptions occur near the surface, they produce the so-called Maars, circular craters filled by a lake and with steep walls. Lagoa do Congro offers a text-book quality example: the level of the lake lies about one hundred meters lower than the surrounding ground.