Transcript Rock Cycle, Igneous, and Sedimentary Rocks PowerPoint

Formation of Sedimentary Rocks
Formation of Sedimentary Rocks
• Much of Earth’s surface is covered with sediments.
• Sediments are pieces of solid material that
have been deposited on Earth’s surface.
• When sediments become cemented together,
they form sedimentary rocks.
• The formation of sedimentary rocks begins when
weathering and erosion produce sediments.
Formation of Sedimentary Rocks
Lithification
• Lithification includes the physical and chemical processes
that transform sediments into sedimentary rocks.
• The weight of overlying sediments forces the sediment
grains closer together, causing the physical changes.
• Layers of mud shrink as excess water is squeezed out.
Formation of Sedimentary Rocks
Lithification
• Sand resists additional compaction during burial.
• Grain-to-grain contacts in sand form a supporting
framework that helps maintain open spaces
between the grains.
Formation of Sedimentary Rocks
Cementation
• Cementation occurs when mineral growth
cements sediment grains together into solid rock.
Formation of Sedimentary Rocks
Features of Sedimentary Rocks
• Bedding, or horizontal layering, is the primary
feature of sedimentary rocks.
• The type of bedding depends upon the method
of transport.
• The size of the grains and the material within the
bedding depend upon many factors.
Formation of Sedimentary Rocks
Other Features of Sedimentary Rocks
• Small sedimentary features such as ripple marks
are also preserved in sedimentary rocks.
• If a rippled surface is buried gently by more
sediment without being disturbed, it might later
be preserved in solid rock.
Formation of Sedimentary Rocks
Features of Sedimentary Rocks
Evidence of Past Life
– Fossils are probably the best-known features of
sedimentary rocks.
– Fossils are the preserved remains, impressions, or any
other evidence of once-living organisms.
– Fossils are of great interest to Earth scientists because
fossils provide evidence of the types of organisms that
lived in the distant past, the environments that existed in
the past, and how organisms have changed over time.
Types of Sedimentary Rocks
Types of Sedimentary Rocks
• The classification of sedimentary rocks is based
on the materials they are made of.
• There are three main groups of sedimentary
rocks: clastic, organic, and chemical.
Types of Sedimentary Rocks
Types of Sedimentary Rocks
Types of Sedimentary Rocks
Clastic Sedimentary Rocks
-They are the most common type of sedimentary rocks.
- They are made from the fragments of previous rocks.
Clastic Rock Examples
• Big chunks- rock stew= Breccia

Small pebbles, clay and
sand are glued together
to make conglomerate.
More Clastic Rocks
• Small sand grains
only is sandstone.
•Clay particles in layers
is shale.
Types of Sedimentary Rocks
Chemical Sedimentary Rocks
• During chemical weathering, minerals can be
dissolved and carried into lakes and oceans.
• As water evaporates from lakes and oceans, the
dissolved minerals are left behind.
• The three most common evaporite minerals are
calcite (CaCO3), halite (NaCl), and gypsum
(CaSO4).
• This is also how caves form.
Types of Sedimentary Rocks
Organic Sedimentary Rocks
– They are formed from the remains of once-living
things.
– The most abundant organic sedimentary rock is
limestone, which contains shells.
– Coal forms from the remains of plant material.
Types of Sedimentary Rocks
Section Assessment
2. The following are which type of
sedimentary rock?
C coal
___
A sandstone
___
E limestone
___
A. clastic
A shale
___
A conglomerate
___
B rock gypsum
___
D. A and B
A breccia
___
B. chemical
C. organic
E. B and C
Metamorphic Rocks
• Heat, pressure and chemical changes can
change any rock into a metamorphic rock.
• Metamorphism is the changing of a solid rock
from one type to another through heat, pressure,
and/or chemical changes.
Metamorphic Rocks
Types of Metamorphism
• Different combinations of temperature and
pressure result in different types of
metamorphism.
• Large belts of regional metamorphism are
produced when high temperature and pressure
affect large regions of Earth’s crust.
Metamorphic Rocks
Types of Metamorphism
• Geologists have
divided the regional
metamorphic belt
that has been
mapped in the
northeastern
United States belt
into zones based
upon the mineral
groups found in
the rocks.
Metamorphic Rocks
Types of Metamorphism
• A local effect called contact metamorphism
occurs when molten rocks, such as those in an
igneous intrusion, come in contact with solid rock.
• High temperature
and moderate-tolow pressure
form the mineral
assemblages that
are characteristic
of contact
metamorphism.
Metamorphic Rocks
Metamorphic Textures
• Metamorphic rocks are classified into two
textural groups: foliated and nonfoliated.
– Foliated metamorphic rocks have parallel layers or
bands of minerals.
– Examples are schist and gneiss.
Foliated Rocks
Slate
Gneiss
Metamorphic Rocks
Metamorphic Textures
– Unfoliated rocks do not have parallel
layers or bands.
– Quartzite and marble are two common
examples of nonfoliated rocks.
Parent and Daughter Rocks
A parent is the existing rock that metamorphoses
into the new daughter rock. Here are examples:
Parent
Daughter
Shale--------
Slate
Shale--------
Schist
Granite------
Gneiss
Sandstone-
Quartzite
Limestone--
Marble
Chapter Resources Menu
Study Guide
Section 6.1
Section 6.2
Section 6.3
Chapter Assessment
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Section 6.1 Study Guide
Section 6.1 Main Ideas
• The processes of weathering, erosion, deposition, burial, and
lithification form sedimentary rocks.
• Clastic sediments are rock and mineral fragments produced
by weathering and erosion. They are classified based on
particle size.
• Sediments are lithified into rock by the processes of
compaction and cementation.
• Sedimentary rocks can contain depositional features such as
horizontal bedding, cross-bedding, and ripple marks.
• Fossils are the remains or other evidence of once-living things
that are preserved in sedimentary rocks.
Section 6.2 Study Guide
Section 6.2 Main Ideas
• There are three main classes of sedimentary rocks: clastic,
which are formed from clastic sediments; chemical, which are
formed from minerals precipitated from water; and organic,
which are formed from the remains of once-living things.
• Clastic sedimentary rocks are classified by particle size
and shape.
• Evaporites are chemical sedimentary rocks that form
primarily in restricted ocean basins in regions with high
evaporation rates.
• Limestone, composed primarily of calcite, is the most
abundant organic sedimentary rock. Coal is another
organic sedimentary rock.
• Sedimentary rocks provide geologists with information about
surface conditions that existed in Earth’s past.
Section 6.3 Study Guide
Section 6.3 Main Ideas
• Metamorphic rocks are formed when existing rocks are
subjected to high temperature and pressure, which cause
changes in the rocks’ textures, mineralogy, and composition.
• The three main types of metamorphism are regional, contact,
and hydrothermal.
• Metamorphic rocks are divided into two textural groups:
foliated and nonfoliated.
• During metamorphism, minerals change into new minerals
that are stable under the conditions of temperature and
pressure at which they formed.
• The rock cycle is the set of processes whereby rocks
continuously change into other types of rock.
Chapter Assessment
Multiple Choice
1. What is it called when sediments are laid down
on the ground or sink to the bottoms of bodies
of water?
a. erosion
c. deposition
b. transport
d. lithification
Erosion is the removal of surface. Transport is the
movement of eroded materials from one location to
another. Lithification is the chemical and physical
processes that transform sediments into
sedimentary rocks.
Chapter Assessment
Multiple Choice
4. Which of the following is an example of a
nonfoliated metamorphic rock?
a. schist
c. gneiss
b. slate
d. quartzite
Unlike foliated rocks, nonfoliated metamorphic rocks lack
mineral grains with long axis in one direction. Schist,
slate, and gneiss are all foliated rocks.
Chapter Assessment
Multiple Choice
5. What is the horizontal layering that is a primary
characteristic in sedimentary rocks called?
a. bedding
c. metamorphism
b. cementation
d. ripple marks
Bedding can range from a millimeter thick layer of shale
to sandstone deposits several meters thick. The type of
bedding depends upon the method of transport.
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