A cone of lava fragments built on the surface
of a lava flow pouring into a body of
water, usually the sea, is called a littoral cone ("littoral" refers to
a shoreline). Lava entering the ocean heats and boils seawater, often generating
steam explosions that hurl tephra onto the
shore, including spatter, bombs,
lapilli, and, rarely, limu.
As the various tephra accumulates on the shoreline, a well-developed cone
may be created.
|Tephra generated by steam explosions built this small
littoral cone along the southern shoreline of Kilauea Volcano, Hawai'i.
Note pahoehoe flow nearing the ocean below the cone. Credit: L. Keszthelyi
/ U.S. Geological Survey
AND PLANETARY SCIENCE