WeatheringWeathering

WeatheringWeathering is the breaking is the breaking down of rocks and other down of rocks and other materials on the earth’s materials on the earth’s surfacesurface

In other words,In other words, WeatheringWeathering is when rocks are broken is when rocks are broken

into soil, sand, and into soil, sand, and sedimentsediment (tiny pieces or (tiny pieces or

particles).particles).

WeatheringWeathering involves two involves two processes that often work processes that often work together to decompose or together to decompose or

break down rocks.break down rocks.

What are 2 Types of What are 2 Types of Weathering?Weathering?

Chemical Chemical & &

MechanicalMechanicalWeatheringWeathering

Chemical weatheringChemical weathering, or , or decomposition, takes place decomposition, takes place when some of the rock’s when some of the rock’s minerals are changed into minerals are changed into different substances.different substances.

Chemical processes that Chemical processes that cause weatheringcause weathering

•Dissolution- Soluble compounds such as limestone are dissolved. This often forms caves.

•Acid dissolves minerals in rocks (examples: carbonic acid, acid rain and plant acid)

•Acid rain can weaken rocks, corrode metal and even kill trees.•Oxygen combines with iron minerals and sulfur minerals changing the composition of the rock and forming rust. This is called oxidation.

Chemical processes that Chemical processes that cause weatheringcause weathering

•Dissolution- Soluble compounds such as limestone are dissolved. This often forms caves.

•Acid dissolves minerals in rocks (examples: carbonic acid, acid rain and plant acid)

•Acid rain can weaken rocks, corrode metal and even kill trees.•Oxygen combines with iron minerals and sulfur minerals changing the composition of the rock and forming rust. This is called oxidation.

Plant acid?Plant acid?

Lichens such as these growing on the rocks in the picture can produce weak acids that react with the rock.

Chemical processes that Chemical processes that cause weatheringcause weathering

•Dissolution- Soluble compounds such as limestone are dissolved. This often forms caves.

•Acid dissolves minerals in rocks (examples: carbonic acid, acid rain and plant acid)

•Acid rain can weaken rocks, corrode metal and even kill trees.•Oxygen combines with iron minerals and sulfur minerals changing the composition of the rock and forming rust. This is called oxidation.

Acid rain…what is the Acid rain…what is the cause?cause?

How acid rain forms…

What causes it?What causes it?

What are the effects?What are the effects?

Acid Rain

1908 to 1969

Acid rain has eaten away this limestone statue.

3000 year old Egyptian Obelisk

3000 year old Egyptian Obelisk after 100 years in NY

http://www.epa.gov/acidrain/educatihttp://www.epa.gov/acidrain/education/site_students/acid_anim.htmlon/site_students/acid_anim.html

Chemical processes that Chemical processes that cause weatheringcause weathering

•Dissolution- Soluble compounds such as limestone are dissolved. This often forms caves.

•Acid dissolves minerals in rocks (examples: carbonic acid, acid rain and plant acid)

•Acid rain can weaken rocks, corrode metal and even kill trees.•Oxygen combines with iron minerals and sulfur minerals changing the composition of the rock and forming rust. This is called oxidation.

Oxidation…what is it?Oxidation…what is it?

Oxidation reactions involve a increase Oxidation reactions involve a increase in oxidation state--in other words, the in oxidation state--in other words, the transfer of electrons from a compound transfer of electrons from a compound that is oxidized to the compound that that is oxidized to the compound that

oxidizes it. Oxygen gas is a major oxidizes it. Oxygen gas is a major component of Earth's atmosphere and component of Earth's atmosphere and is fairly reactive--so much so, in fact, is fairly reactive--so much so, in fact,

that it's good at combining with metals that it's good at combining with metals and compounds in minerals, oxidizing and compounds in minerals, oxidizing

or "rusting" them.or "rusting" them.

Huh??Huh??

the interaction between the interaction between oxygenoxygen molecules and all the molecules and all the different substances they may different substances they may

contact contact

OxidizationOxidizationOxidation turned these rocks in Nevada's Valley of Fire red.

Chemical processes that Chemical processes that cause weatheringcause weathering

•Dissolution- Soluble compounds such as limestone are dissolved. This often forms caves.

•Acid dissolves minerals in rocks (examples: carbonic acid, acid rain and plant acid)

•Acid rain can weaken rocks, corrode metal and even kill trees.•Oxygen combines with iron minerals and sulfur minerals changing the composition of the rock and forming rust. This is called oxidation.

Dissolution-forming caves?

Easy answer…when rain water Easy answer…when rain water seeps into the ground and seeps into the ground and

dissolves the limestone dissolves the limestone underneath.underneath.

Linville Caverns,North Carolina