3-1 Notes Mountains

How can a solid (like rock) fold? Think About… How can a solid (like rock) fold?

Mountains Form Along Plate Boundaries The top of Mt. Everest contain rocks and fossils from the ocean. How is this possible?

Mountains Form Along Plate Boundaries A sea once covered the area that is now Mount Everest

Mountains Form Along Plate Boundaries When an oceanic plate collides with a continental plate, it sinks.

Mountains Form Along Plate Boundaries As the oceanic plate sinks, some sea-floor material can scrape off onto the continental plate.

Mountains Form Along Plate Boundaries This happened as the Indian Plate converged with the Eurasian Plate.

Mountains Form Along Plate Boundaries Eventually, the oceanic crust of the Indian Plate was completely destroyed by subduction, and continental- continental collision began.

Mountains Form Along Plate Boundaries As the mountains formed, the material that was once on the sea floor is now on top of a mountain.

Mountain Ranges and Belts Mountain- an area of land that rises steeply from the land around it.

Kilimanjaro, Tanzania (Africa)

Mt. Fuji, Japan

Denali, Alaska (United States)

Matterhorn, Switzerland (Europe)

Annapurna, Nepal 10th tallest in the world- 8,091 m

K2, Pakistan 2nd tallest in the world- 8,611 m

Mt. Everest, Nepal 1st tallest in the world- 8,848 m

Mountain Ranges and Belts A single mountain is rare. Most mountains belong to ranges.

Mountain Ranges and Belts Range- a long line of mountains that were formed at the same time by the same process.

Mountain Ranges and Belts Mountain ranges that are close together are called mountain belts.

Mountain Ranges and Belts Example: The Rocky Mountain belt contains about 100 different ranges.

Mountain Ranges and Belts Most of the world’s mountain belts are located along tectonic plate boundaries.

Mountains, Rocks, and Sediment Remember that while mountains are being built up, they are also being worn away by erosion!

Mountains, Rocks, and Sediment As long as mountains are being pushed up faster than they are being worn away, they will continue to grow bigger.

Mountains, Rocks, and Sediment Young mountains tend to be tall and steep.

Mountains, Rocks, and Sediment Older mountains are more rounded and worn away.

Mountains, Rocks, and Sediment If the tectonic plates stopped moving, eventually all the land on Earth would be flat due to erosion.

Folded Mountains Rocks can bend when stress is applied slowly over a long period of time.

Heat also helps rocks bend. Folded Mountains Heat also helps rocks bend.

Folded Mountains Folded Mountain-a mountain that forms as continental crust crumples and bends into folds.

Folded Mountains Folded mountains can form at Oceanic-Continental Subduction zones OR Continental- Continental Collision zones.

Example: Himalayas

The formation of the Himalayas can be described in 3 steps: Folded Mountains The formation of the Himalayas can be described in 3 steps:

Folded Mountains 1. Convergent Boundary Develops Oceanic crust sinks under continental crust The edge of the continental crust begins to crumple.

Folded Mountains 2. Continental Collision Begins Eventually, all the oceanic crust is destroyed and continental collision begins. Volcanoes eventually stop erupting and the mountains continue to be pushed up higher.

Folded Mountains 3. Collision Continues The two continents continue to push the rocks up into mountains that are growing taller year after year.

Earthquakes in these areas can also push mountains up higher. Folded Mountains Earthquakes in these areas can also push mountains up higher.

Fault-Block Mountains Fault-Block Mountains- mountains that form as blocks of rock move up or down along normal faults.

Fault-Block Mountains In the Southwest U.S., hundreds of fault block mountain ranges line up in parallel rows along normal faults.

Fault-Block Mountains There are 2 steps in the formation of fault block mountains:

Fault-Block Mountains 1. Lithosphere bends upward and breaks into blocks separated by faults as it is heated by the mantle.

Fault-Block Mountainns 2. As the lithosphere stretches, blocks of rock tilt or drop down between the faults to form mountains and valleys.

Fault-Block Mountains Fault-block mountains form as stress is released through earthquakes over and over.

Fault-Block Mountains Even the most powerful earthquakes only move rocks a small number of meters.

Fault-Block Mountains It takes millions of years and earthquakes to build up large fault-block mountain ranges, like the Sierra Nevada range in California.

Fault-Block Mountains All mountains take millions of years to erode.

Review 1. A folded mountain belt is located far from the edge of a present-day tectonic plate boundary. This mountain belt likely formed E. when two oceanic plates collided. F. as the result of volcanic activity G. when two continental plates collided. H. when blocks of crust moved along faults

Review 2. Folded mountains form at tectonic boundaries where E. new ocean crust is formed. F. plates move toward each other G. plates move away from each other H. plates move horizontally past each other

Review 3. Blocks of rock that have tilted along faults are common E. where two oceanic plates collide F. along subduction zones G. where two continental plates collide H. along ocean spreading centers