Weathering and Erosion

By: Sam Mims

What is Weathering?

Change of appearance from being outside for a very long time. And

when weather changes the way the color, texture, composition or form of objects that are exposed.

Mechanical Weathering

Mechanical weathering is the process of breaking big rocks into little ones. This process usually happens near the surface of the planet. Temperature also affects the land.


The cool nights and hot days always cause things to expand and contract. That movement can cause rocks to crack and break apart.

In this photo, you can see onion like layers that the weathering took away from the rock

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What Is Mechanical Weathering

Chemical Weathering

Any of the various weathering processes that cause exposed rock to undergo chemical decomposition and changing the chemical(s).


Oxidation(reaction of a substance with oxygen) makes rocks softer. It is similar to an iron bar rusting. Another example, is granite turning into clay over time.

This is a picture of and Iron sculpture rusting after many years outside.

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Biological Weathering

Biological weathering is breaking down the molecular substances in minerals. It also includes plants and animals affecting the environment.


There are things called lichens (combinations of fungi and algae) which live on rocks. Lichens slowly eat away at the surface of rocks.

Tree roots can grow into fractures in a rock and pry the rock apart.

In this picture, a tree root grows into the rock that is under it.

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What is erosion?

Erosion is the action of surface processes (such as water flow or wind) that remove soil, rock, or dissolved material from one location on the Earth's crust.

Wind Erosion

Wind erosion usually occurs in very sandy, bare and soily areas. It happens when it is very windy and the wind brings up the soil/sand on the ground and eat at the surface of a rock/surface.

Sediment Sizes:

Dirt, Sand, Pebbles


Wind erosion can be very dangerous and can blow soil into houses and other landforms. In the grand canyon, there are many different rocks that are affected by wind erosion.

In this picture, wind has destroyed this rock into almost nothing.

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Wind Erosion: The Problem

Water Erosion

Erosion causes anywhere where a small portion of water is. It happens when the water rides a piece of land and slowly eats away at the land mass it is riding on.

Sediment Sizes:

Any piece of water


The Colorado river eroded pretty much all of the grand canyon and still to this day erodes the river bank of the colorado river.

In this picture, this river eroded the side of this canyon.

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Erosion by Gravity

Since gravity holds objects to the ground on earth, gravity can cause rock sediments to move down hills, mountains, etc.

Rock Sediments:

Anything can be affected by Gravity erosion.


Water running down all the mountains and valleys is pulled down by this force of gravity. Wind is ultimately a result of air molecules being held to the Earth's surface due to gravity.

In this picture, the land on the hill fell down because gravity pulled it down.

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Erosion by glaciers

As a glacier moves, the glacier slowly melts and goes into the ground underneath. it picks up the pieces of rocks and carries it along with the glacier.

Sediment Sizes:

Only small rocks underneath the surface of the ground can be picked up with the glacier.


Tens of thousands of years ago on the group of islands now known as the British Isles, glaciers covered nearly everything. As the glaciers move, they created a whole different landscape there.

In this picture, the glaciers are moving and picking up the rocks.

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