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Sedimentary Rock
c. Classify rocks by their process of
formation.
d. Describe processes that change rocks
and the surface of the earth.
Sedimentary Rock
 Formed from particles of sediment
deposited by wind and water.
 Sediment is small pieces of solid
materials that come from rocks or
living things.
Stratification
Yes, all these rocks are layered
or “stratified.”
Weathering
The process by
which exposed rock is
broken down into
small pieces by the
elements of nature
(wind, rain, ice,
chemical actions,
plants, etc.)
Origins of Sedimentary Rock
 Wind, water, ice, sunlight, and gravity
all cause rock to physically weather into
fragments.
 Through erosion, these rock and mineral
fragments, called sediment, are moved
from one place to another.
 The sediment is deposited in layers, and
eventually newer layers cover the older
layers.
Erosion
Occurs when water
or wind loosens rock
and soil and carries it
away.
Deposition
 The process by
which the sediment
settles out of the
water or air carrying
it.
 Sediment is
deposited when the
wind or water
slows down.
Compaction
 As the sediments settle
they will loosely fit on
top of each other.
 As the years go by,
more and more
sediment is added.
 The bottom layers get
compacted by the
weight of the layers
above them.
Cementation
 While compaction is
going on, minerals in the
rock slowly dissolve.
 The dissolved minerals
seep into the spaces
between the compacted
sediment.
 They crystallize and
glue the sediments
together.
Lithification
The process by which sediment
becomes sedimentary rock.
From Green word “lithos,”
which means rock.
Erosion
Deposition
Compaction
Types of Sedimentary Rock
 Clastic: formed when
rock fragments are
squeezed together.
 Organic: (biological)
formed from the
remains of living things.
 Chemical: formed
when dissolved
minerals crystallize.
Conglomerate and Breccia
 Formed from a mixture
of rock fragments of
different sizes.
 Conglomerate has
rounded edges.
 Breccia has larger
fragments with sharp
edges
Sandstone
Formed from sand
on beaches,
ocean floors, river
beds, and deserts.
Mainly quartz.
Shale
 Clastic rock from
from tiny particles of
clay.
 Water deposits tiny
clay particles in thin
layers.
 Feels smooth and
splits easily into flat
sheets.
Organic Sedimentary Rock
Formed from the
remains of plants
and animals that
were deposited in
thick layers.
Also called
biological rock.
Coal
 Formed from the
remains of ancient
swamps.
 As layer upon layer of
dead plants built up,
the bottom layers
were compacted into
coal.
 Stored chemical
energy from
Limestone
 Formed from the shells
of ancient sea animals
and plants.
 Shells fall to the
bottom of the ocean in
layers, some 100’s of
meters thick.
 Compaction creates
limestone.
Chalk
Formed from the
shells of ancient sea
life.
Creates layers 100’s
of feet thick.
White Cliffs of
Dover
Chemical Sedimentary Rock
Formed when
water with
dissolved minerals
evaporates.
The left behind
minerals will
crystallize.
Halite
Rock Salt
Formed from
seas and oceans
that dried up.
The salt forms
large crystals.
Gypsum
Made from
calcium
deposits.
Used to make
sheet rock for
homes.