Tuff Cone - John Seach

Tuff cones are less common than cinder cones. They are formed by magma-water eruptions (phreatomagmatic eruptions).
They have steep sides (>25 degrees), and crater floors which lie above ground level.

Surtseyan eruptions construct tuff cones when continuous supplies of large quantities of water enter into contact with rising magma. Their formation requires a more abundant water supply, and explosions at greater depths than those needed to build tuff rings. The resulting cones are often 100 m to 300 m high and 1 to 1.5 km across. Tuff cones have deep, broad craters (narrower and steeper than those of tuff rings). The eruptions may last for several months.