Landforms: Erosion & Mountain Building

What kind of erosion is occuring on the  upper slopes of Mount Rainier?  

GLACIAL EROSION:   GLACIERS ARE SCRAPING AWAY THE SIDES OF THE VOLCANO OVER THOUSANDS OF YEARS.  

Yosemite Valley, California was sculpted out by glaciers during the last ice age, leaving a bowl shaped valley with steep sides.

What kind of erosion sculpted the smooth walls of this canyon?  

EROSION: SAND & WIND SCULPT THE ROCKS OVER      THOUSANDS        OF YEARS. WIND EROSION

What type of erosion created the deep canyon of the Colorado River?

WATER EROSION: Water cuts through layers of rock over thousands of years.

Mount St Helens, before the eruption of 1980.

The eruption of Mount St Helens, May 1980 The eruption of Mount St Helens, May 1980.   Super heated gasses from the blast flash-melted snow and ice and caused a massive mudflow.   A giant hole was formed at the top and side from the blast.

Mount St Helens today:  Mountain building continues as a dome is built up in the crater.

Mountain Building GEOLOGY GEOLOGY

The earth has many  layers inside with a solid inner core.

Underneath the earth's crust is a molton layer of very thick, liquid magma called the mantle.

The earth's crust is broken into large pieces called plates The earth's crust is broken into large pieces called plates.  These plates can move because they are on top of the mantle layer.

Over long periods of time, the earth's plates have moved and changed locations.

We see evidence of fossils on all 7 continents. 

The San Andreas Fault, California, (seen from an airplane The San Andreas Fault, California,  (seen from an airplane.) One plate is moving north and one is moving south.

The Teton Mountains in Wyoming were created by a slip fault - one piece of the earth's crust is uplifted (the Tetons) and one piece of the earth's crust is sinking (the valley floor).

The Olympic Mountains were created from a subduction zone, where one plate slips under another plate.  

SUBDUCTION ZONE: One plate slips under another plate.

 

  Volcanoes ring the Pacific Ocean showing where the oceanic and continental plates collide.

This is one of the many volcanoes in the Aleutian chain off the coast of Alaska.

Cascade Volcanoes, Oregon:  Looking north from Middle Sister:  Belknap Crater, Mt. Washington, Three Fingered Jack, Mt. Jefferson, and Mt. Hood.

Scientist hypothesize that the India landmass drifted into the Asian plate about 10 million years ago.    This created the tallest mountains in the world, the Himalayan Mountains.

Review:  How are mountains made?

Mountains can be made by: 1 Mountains can be made by: 1.  Plates colliding, causing some parts of the earth's crust to be uplifted. 2.  Volcanoes, like the ones seen all along the "Ring of Fire".

Review:  How are mountains torn down or eroded away?

Erosion can be caused by: 1.  Water (like the Grand Canyon) 2.  Wind erosion (like in the desert Southwest) 3.  Glaciers (like on Mount Rainier) 4.  Mudflows - water mixed with earth materials (like when Mount St. Helens erupted. 5.  People can cause erosion too by removing plants from the ground, making wind or water erosion more likely to happen.