SEDIMENTARY ROCKS, METAMORPHIC ROCKS, AND AGE DETERMINATION

SEDIMENTARY ROCKS,
METAMORPHIC ROCKS,
AND AGE
DETERMINATION


SED-MET ROCKS-AGE
• Sedimentary rock family
• Definition and Explanation
• comprised of sediments
• accumulated from physical and or
chemical processes mostly in large
bodies of water
• consolidated through lithification


SED-MET ROCKS-AGE

• Factors and concepts related to rock formation
• weathering--”breaking down” of rock
materials at or near surface of Earth
• chemical--decomposition
of materials and
chemical
formation of new substances through
removal of or additions to the weathered
material
• physical or mechanical--disintegration
of
mechanical
materials with no new substances forming

SED-MET ROCKS-AGE
• Erosion
• removal or transportation of material by
stream water, glacial ice, wind, and
gravity
• eroded materials may eventually
accumulate in large amounts
• Lithification
• compaction and cementation of
sediments to become rocks


SED-MET ROCKS-AGE
• Stratification
• accumulations in layers (strata or beds)
and is the most common occurrence of
this family of rock
• Law of superposition
• in a series of strata, each layer is older
than the one above and younger than the
one below--this reflects a relative age
relationship between layers


Stratification in Sedimentary Rocks

SED-MET ROCKS-AGE
• Sedimentary rock types
• three types based on the way they form;
clastic (detrital), chemical inorganic, and
organic
• clastic
• sediments accumulated primarily by
physical processes as deposits from
stream water, glacial ice, wind, etc. then
lithified to rock


SED-MET ROCKS-AGE
• Wentworth’s sediment size
classification is used to name the
specific clastic rock in the detrital class


Wentworth’s Scale of
Sedimentary Particles


Different colors of beach sand in the world


CLASTIC ROCKS


Detrital (Clastic) Sedimentary Rocks
Larger grained

Conglomerate

Breccia


Detrital (clastic) Sedimentary Sandstones
Graywacke

Arkose

Quartz Sandstone


Detrital (clastic) Sedimentary Rocks
Smaller Grained
Claystone

Siltstone

Shale


SED-MET ROCKS-AGE
• biological (organic) rocks
• accumulation of animal shells or plant
material then lithified--particle size is
not important in naming biological rocks


SED-MET ROCKS-AGE

BIOLOGICAL OR ORGANIC ROCKS


SED-MET ROCKS-AGE
White Cliffs of Dover


COAL SERIES
buried plants

Peat

bituminous
lignite

anthracite
methane
coal gas


SED-MET ROCKS-AGE
Biological (organic) formed chert


SED-MET ROCKS-AGE
• chemical (inorganic) rocks
• formed from chemical reactions in the
oceans or large bodies of water

CHEMICAL OR INORGANIC ROCKS


Lakes formed from Glaciation

Lake Bonneville


Evaporite deposits in Death Valley, California


SED-MET ROCKS-AGE

Chemically (inorganic) formed chert---nodules of
chert caused by replacement of silica for bedrock—is
present in the local Burlington limestone bedrock in
this area