are small spatter cones form on the top of a basaltic lava flow. They
usually form on the surface of a pahoehoe lava flow. Small bits of
lava are forced through a small opening in a vent and cools quickly.
The small bits pile up on each other until steep sides are formed.
Soon a stack begins to form. They form on top of a lava flow instead
of from a direct lava vent. Hornitos are not very strong because they
do not have anything to hold them down.