Chapter 20 – Mountain Building. Topics to be Covered: Crust – Mantle Relationships Convergent Boundary Mountains Uplifted Mountains Fault – Block Mountains. Earth’s Topography. Most of the Earth’s elevations are concentrated around 2 modes.
Topics to be Covered:
“Because of different densities and thickness of continental and oceanic crust.”
Sinks lower in the water
The process of the crust rising due to the removal of overlying material.
Plates are colliding
Folding, faulting, metamorphism, volcanoes
- one oceanic plate is subducted under another, cause the sinking plate to melt.
- As magma rises upward an island arc of volcanic mountains is formed.
Example: Mt. Pinatubo, Philippine Islands
- Oceanic crust is subducted under continental crust.
- Subducted oceanic crust melts.
- Magma rises upward forming a volcanic mountain range on the continental crust.
Example: Andes Mountains, South America
- Both pieces of crust have relatively low density and cannot be subducted.
- Plate will instead push together and get deformed (folded, faulted).
- This will build up thick areas of crust, thus creating the tallest mountains on Earth.