Hornitos are conical, or pipe-like, structures built up by lava spattering or being ejected through an opening in the crust of a lava flow.
[1] [3] High pressure causes lava to ooze and spatter out.
The lava builds up on the surface and solidifies creating the initial structure.
Hornitos can grow and exceed 10 meters in height.
Some classic examples of hornitos have been described, or depicted, from volcanoes including El Jorullo, Mexico which was visited by Alexander von Humboldt in 1803; Kilauea Hawaii; and Oldoinyo Lengai, Tanzania.