Physical Geology

Chapter 11Part 2 – Mountain Building

Definition• A mountain is the most extreme type of

deformation• Relatively small “wrinkles” in the earth’s

crust may soar from 1 to 8 km above sea level

• A mountain is a piece of land that is higher than a hill and stands much higher than the land around it.  Mountains have steep sides and a pointed or rounded top.  The top of a mountain is very cold.  Mountains are created over long periods of time by tremendous forces of the earth.

Range – a group of adjacent mountains related by shape and structure

System – a group of adjacent ranges

Belts – the two major mountainous regions of the world; Eurasian-

Melanesian & Circum-Pacific belts

How do mountains form? It’s all plate tectonics!

Types of Mountains• Folded

and Plateaus

• Faulted• Domes• Volcanic

Blossom Peak, Post Falls, Idaho

Folded Mountains• Compression stress squeezes up

accordion-like folds• May also result in formation of

uplifted, broad, flat plateaus• Himalayas, Rockies, Appalachians,

Urals, parts of the Alps

Types of Folds

Plateau

Faulted Mountains• Vertical movement at fracture zones• Tilted blocks, lift or drop at single faults• Uplift at double faults• Sierra Nevada, Tien Shan, western

foothills of the Rockies (Basin/Range region)

Typical Fault Block Mountains

Fault block valley

Fault block ridge

Death Valley

Basin and Range

Domes and Basins

• Gentle upwarping or downwarping of crustal rock produce domes and basins

• Erosion of these structures results in an outcrop pattern that is roughly circular or elongated

• Black Hills, Adirondacks, Stone Mountain

Domes and Basins

sandstone

limestone

Crystalline

Metamorphic

core

Volcanic Mountains• Eruptions of gases, magma, cinder/ash

and pulverized surface material• Piles of expelled material form cones that

may stand out from surrounding terrain as mountains– Shield cones– Cinder cones – Composite cones