ROCK CLASS

DESCRIPTION: Broad classification of geological units.

Valid entries:

anthropic
clastic sediment
chemical sediment
intermediate extrusive
intermediate intrusive
felsic extrusive
felsic intrusive
mafic extrusive
mafic intrusive
metamorphic
gneiss
schist
tectonic
unknown
ultramafic intrusive
ultramafic extrusive
volcanic

Addition of ? (e.g. ?tectonic) indicates uncertainty of value