LIMESTONES• Calcite (calcium carbonate) dominates• Fine-grained

– Chalk (cliffs of Dover, England)

• Medium-grained– Oolitic limestones

• Coarse-grained– Coquina (broken shells loosely cemented)

– Fossiliferous limestones

CHERT• Microcrystalline silica (microquartz = silicon dioxide)• Many varieties:

– Flint = gray due to organic matter– Jasper = reddish due to iron oxides– agate = banded structures

• Scots Bay Formation at Ross Creek

EVAPORITES• Precipitated crystals from

– oceans– lakes– rivers

• Halite (sodium chloride)

• Gypsum (hydrated calcium sulfate)

Death Valley, California

COAL

• Compressed, heated thick accumulations of organic matter

• With little detrital sediment to form much ash

• Environment: vegetation in a lush swamp

• Well-known from Carboniferous Period of Nova Scotia

Coalfields of Nova Scotia

FOSSIL FUELS

• Alteration of partly decayed and buried organic matter.

• Coal solid rock

• Petroleum liquid in pore

• Natural gas gas (mostly methane) spaces

• Coal is mostly from terrestrial plant matter, but petroleum and natural gas come mostly from marine animals, plants and micro-organisms