Unit 6 - Mountain Building Flashcards
(18 cards)
What is topography?
The variation of elevations in the crust.
Topography ranges from 0-1 km above sea level to as low as -5 km below sea level.
What type of crust is continental crust?
Granitic and less dense than oceanic crust.
Continental crust is primarily composed of lighter materials compared to oceanic crust.
Define isostasy.
The displacement of the mantle by Earth’s continental and oceanic crust that produces a condition of equilibrium.
What balances the downward force of gravity on the crust?
The upward force of buoyancy resulting from mantle displacement.
This concept can be compared to how boats float.
What are mountain roots?
Large roots required to counterbalance the mass of a mountain.
Roots maintain buoyant support and balance.
What happens to mountain roots when mountains erode?
The roots rise until they are exposed to the surface.
This process is known as isostatic rebound.
What are underwater mountains called?
Seamounts
How deep can mountain roots be compared to mountain heights?
Roots can be many times as deep as mountains are high.
What is orogeny?
All processes that form mountain ranges.
What type of boundaries are most orogenic belts associated with?
Convergent boundaries.
What occurs during oceanic-oceanic convergence?
Island Arc Mountain building, including volcanism, sedimentary rocks, uplift, folding, and faulting.
What happens during oceanic-continental convergence?
Oceanic plate forces continental plate to uplift, causing crust to fold and thicken.
What occurs during continental-continental convergence?
Compressive forces cause rocks to fold, fault, and thicken, breaking into thick slabs along low-angle faults.
What is seafloor spreading?
Magma upwells at a central rift, causing warmer, newer, lighter crust to remain uplifted.
What are uplifted mountains?
Mountains formed when large regions of the Earth are slowly forced upwards as a unit with little structural deformation.
What are fault block mountains?
Mountains formed when tension rifts apart areas of the crust, causing pieces to drop downwards.
What is a graben?
The lowered matter in fault block mountain formation.
What is a horst?
The uplifted matter in fault block mountain formation.
