1. WHAT IS OROGENY? Processes of mtn building
Deformation
Folding and thrust-faulting
Metamorphism
Intrusions: batholiths, etc
Volcanic Activity

2. TYPES OF MOUNTAINS Volcanic: Shield and composite
Fault-block: normal faulting and tension
Folded: compression, reverse faulting
Complex: mixture of most of the above

3. Mauna Loa in
Background
Kilaeua is
Behind Mauna
Loa
Mauna Kea
Shield volcano
Hot Spot
Basalt

4. Kilaeua
Newest ground in
The world
Asthenosphere coming
To the surface

5. Composite Volcano
Mt Rainier
Compressive forces
Subduction zones
Andesitic composition

6. Guagua Pichincha, Ecuador
Quito in foreground
Composite volcanoes explosive

7. Normal fault
Footwall moves
Up relative to
Hanging wall
FOOTWALL
HANGING WALL
Tension forces

8. Tilted fault-block range: Sierra Nevada from east,
Steep side of block fault; Ansel Adams photo

9. Tilted Fault-block
Sierra Nevada from west
Side, low angle
Yosemite valley the result
Of glaciation on low-angle
relief

10. Wasatch Range
From Salt Lake City
Typically fault-
Block system

11. Grand Tetons: Another fault-block system

12. Alternating normal faults lead to a characteristic pattern called a
Horst and Graben system. An area under tension will often have
Multiple mountain ranges as a result.

13. Horst and Graben Landscapes
Figure

14. Basin and range province: tilted fault-block mountains in Nevada.
The results of a horst and graben system. Nevada is under tension
Because of rising magma which is unzipping the system, all the way
From Baja California
Sierra Nevada and Wasatch Ranges part of this system

15. REVERSE FAULTS: Hanging wall moves up relative to footwall
Result of compression: plates colliding
Two types: low-angle or thrust faults, and high-angle reverse faults
Individual layers can move 100’s of kilometers
Alps are a great example

16. Thrust faults main cause
Of folded mountains

17. Appalachian Mountains of the US

18. Atlas Mountains, Northern Africa

19. Classic folded terrain: well-developed anticline

20. ZAGROS MTS
PERSIAN GULF
Alternating
Anticlines and
Synclines

21. High-angle reverse faults
Forms “Sawtooth Mtns”
Flatirons classic example
Sawtooth effect result of
Differential erosion

22. SAWTOOTH RANGE,
IDAHO
Alice Lake
White Cloud peak

23. COMPLEX MOUNTAINS
Tend to have a little of
Everything: volcanoes,
Folds, thrust faults, normal
faults
ALPS
HIMALAYAS

24. ANDES: Classic example

25. ANDES: CLASSIC EXAMPLE OF GENERIC MTNS

26. Compression causes expansion
Layered rock formed
Thrust-faulting
Igneous intrusions: Plutons
Underplating
Regional metamorphism
South American Plate
Nazca Plate

27. ANATOMY OF AN OROGENGIC BELT