Sedimentary Rocks
• How do sedimentary rocks form?
• What are the three types of
sedimentary rocks?
Sedimentary Rocks
• compaction
• clast
• cementation
• chemical rock
• clastic rock
• biochemical rock
Sedimentary Rock Formation
• Mineral and rock fragments can be
transported by water, glacial ice,
gravity, or wind.
• The sediments eventually are
deposited, or laid down, where they
can them accumulate in layers.
Sedimentary Rock Formation (cont.)
• The weight from the layers
of sediment forces out fluids
and decreases the space
between grains during a
process called compaction.
• Compaction can lead to a
process called cementation.
Sedimentary Rock Formation (cont.)
• When minerals dissolved in
water crystallize between
sediment grains, the
process is called
cementation.
• Mineral cement holds the
grains together.
Sedimentary Rock Formation (cont.)
What is the difference
between compaction and
cementation?
Sedimentary Rock Identification
• Sedimentary rocks that are made up of
broken pieces of minerals and rock
fragments are known as clastic rocks.
• The broken pieces and fragments are
called clasts.
• Sediment size alone cannot be used to
determine the environment where a
clastic rock formed.
Sedimentary Rock Identification (cont.)
clastic
from Greek klastos, means
“broken”
Sedimentary Rock Identification (cont.)
• When water becomes saturated with
dissolved minerals, particles can
crystallize out of the water and form
minerals.
• Chemical rocks form when minerals
crystallize directly from water.
The water that once filled this lake bed
was saturated with dissolved halite. The
water evaporated and crystalline rock
salt formed.
National Geographic/Getty Images
Sedimentary Rock Identification (cont.)
• Biochemical rock is a sedimentary
rock that was formed by organisms or
contains the remains of organisms.
• Sometimes the remains or traces of
organisms are preserved as fossils in
biochemical rock.
Sedimentary Rock Identification (cont.)
Chemical and biochemical sedimentary
rocks are common on Earth’s surface.
Sedimentary Rock Identification (cont.)
How do chemical and
biochemical sedimentary
rocks form?
• A clastic sedimentary rock is made of
clasts of minerals or rock fragments.
• When minerals crystallize directly from
water, a chemical sedimentary rock
results.
• A biochemical sedimentary rock contains
the remains of living
organisms or was
formed by
organisms.
National Geographic/Getty Images
During which process does the
weight from layers of sediment
force out fluids and decrease the
space between grains?
A. cementation
B. crystallization
C. compaction
D. evaporation
Which types of rocks are
sedimentary rocks made up of
broken pieces of minerals and
rock fragments?
A. chemical
C. fragmented
B. biochemical
D. clastic
Chemical rocks form when
minerals crystallize directly from
which of these?
A. gas
B. water
C. sediment
D. magma
Do you agree or disagree?
5. Water can dissolve rock.
6. All sedimentary rocks on earth formed
from the remains of organisms that
lived in oceans.