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Chapter 6 Sedimentary and Metamorphic Rock

Weathering and Erosion • Wherever rock is exposed at

Earth’s surface, it is continuously

being broken down by weathering

– a set of physical and chemical

processes that breaks rock into

smaller pieces.

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Weathering and Erosion • Wherever rock is exposed at

Earth’s surface, it is continuously

being broken down by weathering

– a set of physical and chemical

processes that breaks rock into

smaller pieces.

Weathering and Erosion • Sediments are small pieces

of rock that are moved and

deposited by water, wind,

glaciers, and gravity.

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Weathering and Erosion • The formation of

sedimentary rocks begins

when weathering and

erosion produce sediments.

Chemical Weathering • Chemical weathering

occurs when the minerals in

a rock are dissolved or

chemically changed.

• Acid Rain

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Physical Weathering • Physical weathering occurs

when rock fragments break

off of solid rock along

fractures.

Erosion • The removal and transport

of sediment is called

erosion.

• The four main agents of

erosion are: wind, moving

water, gravity, and glaciers.

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Deposition • When transported sediments are

deposited on the ground or sink to the bottom of a body of water, deposition occurs.

• This forms layers of sediment with the largest grains at the bottom. This feature of layering in sedimentary rock is called bedding.

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Graded Bedding

Lithification ( to turn to stone)

• Lithification is the physical and chemical process that

transforms sediment into

sedimentary rock.

• Lithification begins with

compaction and is completed

by cementation.

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Bedding • Sedimentary rocks have

features that help geologists

interpret how they formed.

• The primary feature of

sedimentary rocks is horizontal

layering called bedding.

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Graded Bedding • Bedding in which the particle

sizes increases toward the bottom

layers is called graded bedding.

• Graded bedding is observed in

marine sedimentary rocks that

were deposited by underwater

landslides.

Graded Bedding

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Cross-Bedding • Cross-bedding is formed as

layers of sediment are

deposited across a horizontal surface.

• Cross-bedding is usually

formed by migrating sand

dunes. (Wind erosion)

Cross-Bedding

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Chapter 6.2 Types of Sedimentary Rock

• Describe the types of clastic

sedimentary rocks

• Explain how chemical

sedimentary rocks form

• Describe biochemical

sedimentary rocks

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Clastic Sedimentary Rock • Clastic sedimentary rocks

are the most common type

of sedimentary rock, and

are formed from the

deposits of loose sediments

on the Earth’s surface.

Clastic Sedimentary Rock • Clastic comes from the

Greek work klastos which

means broken.

• A clast is a broken fragment

of a rock = sediment

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Clastic Sedimentary Rock

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Coarse-grained Rocks • Sedimentary rocks

consisting of gravel sized

rock and mineral fragments

are classified as coarse-

grained clastic rocks

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Coarse-grained Rocks • Forms during high velocity

water flows, such as

mountain streams, flooding

rivers, ocean waves, and

glacier meltwater.

Coarse-grained Rocks Conglomerate Breccia

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Medium-grained Rocks • Sedimentary rocks that

contain sand-sized rock

and mineral fragments are

classified as medium-

grained clastic rock

Medium-grained Rocks • These rocks have a high

porosity (open space between grains of sediment)

• Oil, natural gas, and groundwater, can be found in the pore spaces of sandstone.

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Medium-grained Rocks Sandstone

Cross-bedding Ripple marks

(wind) (water)

Fine-grained Rocks • Sedimentary rock

consisting of silt and clay

sized particles are called

fine-grained clastic rocks.

• Forms in swamp and pond

environments.

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Fine-grained Rocks Siltstone Shale

Burgess Shale Fossil (Trilobite)

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Chemical Sedimentary Rock

• When dissolved minerals in water reach saturation, crystal grains precipitate out of solution and settle to the bottom.

• Layers of chemical sedimentary rock form, which are called evaporites.

Evaporite Formation

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Chemical Sedimentary Rock

Rock Salt

Biochemical Sedimentary Rock (organic rock)

• Biochemical sedimentary rocks are formed from the remains of once-living organisms.

• Contain shells, skeletal remains, or decomposed organic matter.

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Biochemical Sedimentary Rock

Limestone Coal

Section 6.3: Metamorphic Rock

• Compare the different types

and causes of

metamorphism.

• Distinguish among

metamorphic textures

• Apply the Rock Cycle

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Recognizing Metamorphic Rock • Metamorphic rocks form

when pre-existing rocks are

exposed to increases in

temperature and pressure.

• Metamorphosis: To change

form.

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Recognizing Metamorphic Rock • When temperature or

pressure becomes high

enough and rocks do not

quite melt, they change

form.

Recognizing Metamorphic Rock • Temperature and pressure

can change the texture,

mineral composition, or

chemical composition of a

rock without melting it.

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Recognizing Metamorphic Rock • The high pressures required

for metamorphism come

from deep burial or from

compression during

mountain building.

Metamorphic Textures • Foliated metamorphic rocks

are characterized by layers and bands of minerals.

• High Pressure causes minerals to flatten out perpendicular to the pressure

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Metamorphic Textures

Foliated

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Metamorphic Textures • Nonfoliated metamorphic

rocks are characterized by

minerals that form blocky

crystal shapes.

• Nonfoliated metamorphic

rocks are not banded.

Nonfoliated

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