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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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can you name these mountains
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
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
What Type of Igneous Structure?
  • Granitic Batholith – Sierra Nevada
mountain building
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
isostasy and isostatic adjustment
Isostasy and Isostatic Adjustment
  • Erosion removes weight
  • Crust rises
  • Eventually uniform thickness
how do rocks react to stress
How Do Rocks React to Stress?
  • Compression
    • Crumpling
  • Tension
    • Stretching
  • Shear Stress
    • Grind past
slide9

Rock Deformation

  • Rocks deform under stress
    • Temporarily
      • elastic deformation
    • Permanently
      • Plastic deformation - folds
      • Brittle deformation - faults
folding
Folding

Compression causes:

Fold mountains and thrust faults

Crustal shortening

Thicker Crust in mountains

topography does not always reflect structure
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
most major mountain belts include fold mountains
Most Major Mountain Belts Include Fold Mountains
  • Compression crumples sediments when plates converge
  • Alpine structure includes complex folds and thrust faults

European Alps

what is a fault
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
what stress produced these faults
What stress produced these faults?

Compression

Tension

Compression

Shear stress

normal and reverse faults
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
what kind of fault
What Kind of Fault?
  • A Reverse fault
what kind of a fault22
What Kind of a Fault?
  • Strike-slip fault
can tension and normal faults produce mountains
Can Tension and Normal Faults Produce Mountains?
  • Fault-Block Mountains
  • Great Basin or Basin and Range
great basin
Great Basin
  • After subduction of Farallon Plate
  • North America moved over a rift zone
basin and range
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
what is the relationship between mountains and plate tectonics
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
what is the relationship between mountains and plate tectonics27
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
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
Evolution of the Appalachians
  • 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
evolution of the appalachians30
Evolution of the Appalachians
  • 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
Identify These Geomorphic Regions

Modoc Plateau

Klamath Mountains

Cascade Ranges

what kind of mountain
What Kind of Mountain?

Composite Cone – Mount Shasta

how did the coast range form
How Did the Coast Range Form?

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

Complex Mountains

slide36

Terrane Map

Aleutian Trench, Alaska

why Alaska gets such big

Earthquakes

Ultimate destination of LA

slide38

Alaska

State made entirely of accreted terranes

sutures, faulting between them

steep topography

Denali

20,320 Mt. McKinley

slide39

Bay Area Terranes

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
What Kind of Fault?

Transform Fault

Strike-slip

Horizontal movement

what region41
What Region?

Flood Basalts

What structure?

identify this geomorphic region
Identify This Geomorphic Region

Central Valley

A sediment-filled basin

what region43
What Region?

Transverse Ranges – Complex Mountains

identify the structure in this geomorphic region
Identify The Structure in this Geomorphic Region

Peninsular Ranges

A Granitic Batholith

what region46
What Region?

Salton Trough

A Graben

what region47
What Region?

What Structure?

what region48
What Region?

Klamath Mountains

Complex Mountains

slide49

Klamath Terranes

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
A – Klamath Mountains
    • 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
What Structure Dominates Nevada?

The Great Basin

Basin and Ranges