Transcript Sedimentary Rocks

Sedimentary Rocks
Sediments

Pieces of solid material that have
been deposited on Earth’s surface by
wind, water, ice, gravity, or chemical
precipitation.
Weathering
A set of physical and chemical processes that break
down rocks into smaller pieces (sediments).
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Physical Weathering:
The minerals remain
chemically
unchanged, rock
fragments simply
break off.
Chemical Weathering:
Occurs when the
minerals in a rock are
dissolved or
otherwise chemically
changed.
Physical Weathering
Chemical Weathering
Weathering Cont…
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Weathering produces rock
fragments know as clastic
sediments, which can range
in size from huge
boulders to microscopic
particles.
They usually have worn
surfaces and rounded
edges caused by physical
abrasion during erosion and
transport.
Some Cool Pictures of What
Weathering Can Do
Erosion: The removal and movement of
surface material from one location to
another
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What are the four
main agents of
erosion?
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wind
moving water
gravity
glaciers
Erosion In Action
Deposition

When sediments are laid down on the
ground, or sink to the bottom of
bodies of water.
Lithification

The physical and chemical processes
that transform sediments into
sedimentary rocks.
Lithification begins with compaction . As
temperature begins to increase with depth,
 sediments begin to experience chemical and
mineral changes that cause cementation.
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The two types of Cementation
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* when a new mineral,
such as calcite or iron
oxide, grows between the
sediment grains
* when existing mineral
grains grow larger (this
can happen if heat is
introduced, or when more
of the same mineral
precipitates out of the
groundwater)
Evidence of past life is visible in
sedimentary rocks as fossils.
Types of Sedimentary Rocks

Clastic Sedimentary Rocks: The most common type of
sedimentary rock. Formed from the abundant deposits of
loose sediments found on Earth’s surface (and can be
further classified by the size of their grains)
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Coarse-Grained: gravel-sized rock and mineral
fragments
Medium-Grained: sand-sized rock and mineral
fragments
Fine-Grained: sedimentary rocks consisting of silt or
mud (logically called siltstone or mudstone)
Chemical Sedimentary Rocks

sediments that
form from the
evaporation of
mineral-rich
water (called
“evaporites”).
The “chemical”
sediments can
then go through
the process of
compaction and
cementation
Organic Sedimentary Rocks

Sediments that are formed from the
remains of once-living things. These
too, can then go through the process
of compaction and cementation
Sedimentary Rocks in N. America