a place where magma (molten rock) and/or gas comes to the surface from within the earth’s core (A1)

Volcanic ejecta

fragments of lava or already solidified rock that is thrown into the air (or ‘ejected’) by a volcanic explosion (A1)

Volcanic ash

volcanic ejecta that is less than .5 centimeters (.2 inch) in diameter comprised of already solid rock, crystals from solid rock, or particles of lava that were thrown up as liquid spray (A1)


a hole left behind when lava cools quickly and traps gases (A1)


volcanic ejecta that is partly liquid when it strikes the ground, flattening out or splashing when it hits (A1)

Relative time scale

as in the geologic time scale, one that expresses age or length in relationship to other periods of time or geologic formations (A1)

Radiocarbon dating

a process for determining the age of organic (carbon-containing) materials using the rate of radioactive decay of Carbon-14, also known as Carbon-14 (C-14) dating (A1)