Volcano
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)
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)
Radiometric dating
establishing an age based on changes in atomic structure (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)