90 likes | 361 Views
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)
E N D
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
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