1. WHAT IS OROGENY?
Processes of mtn building
Distinctive patterns of deposition
eugeocline, miogeocline
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: reverse faults and compression
• 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. 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

14. 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

15. Thrust faults main cause
Of folded mountains

16. Appalachian Mountains of the US

17. Atlas Mountains, Northern Africa

18. Classic folded terrain: well-developed anticline

19. ZAGROS MTS
PERSIAN GULF
Alternating
Anticlines and
Synclines

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

21. SAWTOOTH RANGE,
IDAHO
Alice Lake
White Cloud peak

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