1. M
MOUNTAIN BUILDING

2. Orogeny: The Mountain Building Process
What processes build mountains?
Volcanic activity
Tectonic Activity
- Folding: Bending of rock
-Faulting: Breaking of rock

3. Mountain Building Mountain building processes thicken the crust
Mountains can be twice as thick as the average continental crust ( 70 km VS. 35 km)
Elevation of crust depends on thickness and density
Mountains have deep roots that extend into the mantle
As erosion occurs, mass is lost from the mountain and these roots begin to rise

4. Isostasy: Crust-Mantle Relationships
What is it? ~ Displacement & rebounding of the mantle by Earth’s continental and oceanic crust
Crust and mantle in equilibrium when gravity is balanced by the upward force
Isostatic Rebound: slow process of crust rising as a result of the removal of overlying material

5. Convergent Boundary Mountains
Oceanic-Oceanic:
2 oceanic plates; one descends into mantle, melts, then magma forced upward forming island arc which thickens to form root, displaces the mantle, forming mountain peak

6. Convergent Boundary Mountains
Oceanic-Continental:
Plates come together, create subduction zone, produce major mountain belts due to the descending ocean plate forcing continental plate up; as crust thickens, higher and higher mountains form

7. Convergent Boundary Mountains
Continental-Continental:
Creates tallest mountains (Himalayas); it is the energy from the collision of these plates that that causes the crust to fold and fault; can double the thickness of the crust

8. Divergent Boundary Mountains
Ocean ridges formed from rising convection cells that form in mantle; the divergent boundary bulges upward to form a gently sloping mountain range (longest on Earth)
Mid-Ocean Ridge

9. Non Boundary Mountains
Uplifted Mountains: form when large regions of Earth have been slowly forced upward as a unit.
(this concept is not yet completely understood)

10. Non Boundary Mountains
Fault-Block Mountains: form when large pieces of crust are tilted, uplifted, or dropped downward between large faults

11. Non Boundary Mountains
Volcanic Peaks: volcanoes that form over hot spots form far from any tectonic plate boundaries.
Mount Shasta