Browse Items (1651 total)

coarse grained, light gray, biotite-hornblende

ignimbrite layer in a welded tuff

flinty, columnar jointing, post-batholith volcanic

from large sill

fine grained with pinkish tint

from nearly vertical dike cutting quartz monzonite

pre-batholith volcanic

intrusive plug of quartz monzonite

1:62500

Mounted on thick paperboard
black and white