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Mountain Building and Geologic Structures. Can you name these mountains?. Caledonians. Urals. Appalachians. Alps. Rocky Mountains. Himalayas. Andes Urals Appalachians Caledonians Great Dividing Range Himalayas Alps Rockies. Andes. Great Dividing Range.

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Mountain building and geologic structures l.jpg
Mountain Building and Geologic Structures


Can you name these mountains l.jpg
Can you name these mountains?

Caledonians

Urals

Appalachians

Alps

Rocky Mountains

Himalayas

  • Andes Urals Appalachians Caledonians

  • Great Dividing Range Himalayas Alps Rockies

Andes

Great Dividing Range


Mountain building orogenesis processes l.jpg
Mountain Building (Orogenesis) Processes

What Processes Build Mountains?

  • Volcanic Activity

  • Tectonic Activity

    • Folding – bending of rock

    • Faulting – breaking of rock



What type of igneous structure l.jpg
What Type of Igneous Structure?

  • Granitic Batholith – Sierra Nevada


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Mountain Building

  • Mountain building processes thicken the crust

  • Mountains can be twice as thick as the average continental crust (70 K versus 35 K)

  • Mountains have deep roots


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Isostasy and Isostatic Adjustment

  • Erosion removes weight

  • Crust rises

  • Eventually uniform thickness


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How Do Rocks React to Stress?

  • Compression

    • Crumpling

  • Tension

    • Stretching

  • Shear Stress

    • Grind past


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Rock Deformation

  • Rocks deform under stress

    • Temporarily

      • elastic deformation

    • Permanently

      • Plastic deformation - folds

      • Brittle deformation - faults


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Folding

Compression causes:

Fold mountains and thrust faults

Crustal shortening

Thicker Crust in mountains





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Topography Does Not Always Reflect Structure

A

B

C

  • Some anticlines form valleys

  • Some synclines form ridges

    Rock hardness determines the topography

  • Hard rock forms ridges, soft rock forms valleys



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Most Major Mountain Belts Include Fold Mountains

  • Compression crumples sediments when plates converge

  • Alpine structure includes complex folds and thrust faults

European Alps


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What is a Fault?

  • Faults are fractures in the earth’s crust along which movement has taken place

  • Joints are fractures that have not moved

  • Faults can be a few feet or hundreds of miles long


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What stress produced these faults?

Compression

Tension

Compression

Shear stress


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Normal and Reverse Faults

  • What is normal about a normal fault?

  • What is reversed about a reverse fault?

  • In a NORMAL fault, the upper block (hanging wall) drops under the influence of gravity


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What Kind of Fault?

  • A Reverse fault


What kind of a fault l.jpg
What Kind of a Fault?

  • Normal Fault


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What Kind of a Fault?

  • Strike-slip fault


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Can Tension and Normal Faults Produce Mountains?

  • Fault-Block Mountains

  • Great Basin or Basin and Range


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Great Basin

  • After subduction of Farallon Plate

  • North America moved over a rift zone


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Basin and Range

  • Crustal stretching cause some tilted blocks to slump and forms basins

  • A block surrounded by parallel faults may drop to form a graben

  • The remaining blocks form horst block mountains


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What is the relationship between mountains and plate tectonics?

Some mountains are volcanic (igneous) mountains

  • Convergent Plate Boundaries

    • Cascade Volcanic Mountains

    • Sierra Nevada Granitic Batholith

  • Divergent Plate Boundaries

    • Kilimanjaro in East Africa

    • Mount Hekla in Iceland

  • Hot Spots

    • Mauna Loa in Hawaii


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What is the relationship between mountains and plate tectonics?

  • Many mountains coincide with currently active convergent plate boundaries

    • Andes

    • Himalayas

    • Alps

  • Most of these mountains are complex involving folding, faulting, and volcanism


What is the relationship between mountains and plate tectonics28 l.jpg
What is the relationship between mountains and plate tectonics?

  • Some mountains coincide with OLD plate boundaries

    • Ural Mountains in Russia

    • Appalachians in Eastern United States


Evolution of the appalachians l.jpg
Evolution of the Appalachians tectonics?

  • 600 million years ago

  • Passive margin

  • 500 million years ago

  • Ocean-Continent Convergent Boundary

  • Subduction zone volcanism

  • 350-400 million years

  • Newfoundland-Caledonian collision

  • Africa approaches


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Evolution of the Appalachians tectonics?

  • 250 million years ago

  • Continent-Continent America-Africa

  • Appalachians fold and fault

  • 200 million years ago

  • Divergent rift zone

  • Today

  • Part of Africa left behind

  • Passive margin



Identify these geomorphic regions l.jpg
Identify These Geomorphic Regions tectonics?

Modoc Plateau

Klamath Mountains

Cascade Ranges


What kind of mountain l.jpg
What Kind of Mountain? tectonics?

Composite Cone – Mount Shasta


What region l.jpg
What Region? tectonics?


How did the coast range form l.jpg
How Did the Coast Range Form? tectonics?

Slices of sea floor, folded sediments, island arcs, and terranes from other places accreted to the Coast Range

Complex Mountains


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Terrane Map tectonics?

Aleutian Trench, Alaska

why Alaska gets such big

Earthquakes

Ultimate destination of LA


Terrane formation l.jpg
Terrane Formation tectonics?


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Alaska tectonics?

State made entirely of accreted terranes

sutures, faulting between them

steep topography

Denali

20,320 Mt. McKinley


Slide39 l.jpg

Bay Area Terranes tectonics?

Franciscan Group

Marin Headlands

Nicasio Reservoir

Alcatraz

Permanente

Yolla Bolly

Novato Quarry

Yerba Buena

Richmond

Salinian

Red Rock? Angel Island?

each of these bounded by faults

much more than just San Andreas and Hayward


What kind of fault40 l.jpg
What Kind of Fault? tectonics?

Transform Fault

Strike-slip

Horizontal movement


What region41 l.jpg
What Region? tectonics?

Flood Basalts

What structure?


Identify this geomorphic region l.jpg
Identify This Geomorphic Region tectonics?

Central Valley

A sediment-filled basin


What region43 l.jpg
What Region? tectonics?

Transverse Ranges – Complex Mountains


What region44 l.jpg
What Region? tectonics?


Identify the structure in this geomorphic region l.jpg
Identify The Structure in this Geomorphic Region tectonics?

Peninsular Ranges

A Granitic Batholith


What region46 l.jpg
What Region? tectonics?

Salton Trough

A Graben


What region47 l.jpg
What Region? tectonics?

What Structure?


What region48 l.jpg
What Region? tectonics?

Klamath Mountains

Complex Mountains


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Klamath Terranes tectonics?

this map shows 10

distinct terranes

and many sub-terranes

how do you divide them?

subjective

depends on purpose

how small is too small to

call a terrane?


Slide50 l.jpg

  • A – Klamath Mountains tectonics?

    • Complex Mountains

  • B – Coast Ranges

    • Complex Mountains

  • C – Cascade Ranges

    • Composite Volcanoes

  • D – Modoc Plateau

    • Flood Basalts

  • E – Sierra Nevada

    • Granitic Batholith

  • F – Central Valley

    • Sediment filled basin

  • G – H Great Basin

    • Fault Block Mountains

  • I - Transverse Range

    • Complex Mountains

  • J – Peninsula Ranges

    • Granitic batholiths

  • K – Salton Trough

    • Graben


What structure dominates nevada l.jpg
What Structure Dominates Nevada? tectonics?

The Great Basin

Basin and Ranges


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