background
banded
bedded
black
carbonate
chalk
coast
compressed
crystal
crystalline
earth
earth history
flint
flintstone
formation
geode
geological
geology
gravel
gray
layer
layered
limestone
material
mineral
minerals
natural
nature
outdoor
pattern
pebble
piece
quartz
raw
rock
rough
scientific
sediment
sedimentology
silica
stone
strata
stratified
structure
structures
surface
texture
white