Mechanical and Mechanical and chemical forces chemical forces break down rockbreak down rockWhen you are walking in your When you are walking in your neighborhood how do you neighborhood how do you think the small rocks are think the small rocks are formed?formed?

Mechanical and chemical Mechanical and chemical forces break down rockforces break down rock

Weathering, which Weathering, which is the process by is the process by which natural forces which natural forces break down rock. break down rock.

Mechanical and chemical Mechanical and chemical forces break down rockforces break down rock

There are two There are two ways in which ways in which weathering weathering can occur.can occur.

Physically Physically broken apart broken apart and chemicallyand chemically

Mechanical and chemical Mechanical and chemical forces break down rockforces break down rock

Mechanical Mechanical weathering breaks up weathering breaks up rock by physical rock by physical forces. forces.

Those physical forces Those physical forces split apart rock split apart rock

Mechanical Mechanical weathering can be weathering can be caused by ice caused by ice wedging, pressure wedging, pressure release, plant root release, plant root growth, and abrasion.growth, and abrasion.

Mechanical and chemical Mechanical and chemical forces break down rockforces break down rock

Ice wedging Ice wedging causes mechanical causes mechanical weathering. When weathering. When water freezes in water freezes in the cracks and the cracks and pores of rocks, the pores of rocks, the force of its force of its expansion is strong expansion is strong enough to split enough to split apart rock. apart rock.

Mechanical and chemical Mechanical and chemical forces break down rockforces break down rock

Pressure release is Pressure release is the next method. the next method. Rock deep within Rock deep within the earth’s surface the earth’s surface is under great is under great amounts of amounts of pressure. Over time pressure. Over time the rock is pushed the rock is pushed up to the surface of up to the surface of the earth.the earth.

Mechanical and chemical Mechanical and chemical forces break down rockforces break down rock

When the rock When the rock reaches the reaches the surface the surface the pressure is pressure is released and the released and the rock expands. As rock expands. As the rock expands the rock expands cracks from in it cracks from in it causing causing weathering.weathering.

Mechanical and chemical Mechanical and chemical forces break down rockforces break down rock

Plant Root growth is Plant Root growth is method in method in mechanical mechanical weathering. When weathering. When plants grow in a plants grow in a rock, their roots can rock, their roots can widen the crack and widen the crack and force the rock apart. force the rock apart. Thus mechanical Thus mechanical weathering takes weathering takes place. place.

Mechanical and chemical Mechanical and chemical forces break down rockforces break down rock

Abrasion is the final Abrasion is the final method in method in mechanical mechanical weathering. Water weathering. Water alone can wear alone can wear down rocks, but they down rocks, but they also can move rocks also can move rocks downstream causing downstream causing them to rub together them to rub together and wear down into and wear down into rounded shapes. rounded shapes.

Mechanical and chemical Mechanical and chemical forces break down rockforces break down rock

When elements When elements react with react with water and air water and air they can cause they can cause the breakdown the breakdown of rocks. This is of rocks. This is of course of course chemical chemical weathering. weathering.

Mechanical and chemical Mechanical and chemical forces break down rockforces break down rock

When minerals When minerals in rocks come in rocks come into contact with into contact with air and water, air and water, some dissolve some dissolve and others react and others react and are changed and are changed into different into different minerals.minerals.

Mechanical and chemical Mechanical and chemical forces break down rockforces break down rock

Water is the main Water is the main cause of chemical cause of chemical weathering. weathering.

Water and carbon Water and carbon dioxide mix with dioxide mix with decaying plants decaying plants and breaks down and breaks down rock into smaller rock into smaller pieces. pieces.

Mechanical and chemical Mechanical and chemical forces break down rockforces break down rock

Oxygen is also a Oxygen is also a major factor in major factor in chemical chemical weathering. weathering.

When minerals When minerals dissolve in water, dissolve in water, oxygen in the air oxygen in the air and water combines and water combines with iron to with iron to produce iron oxides produce iron oxides or rust. or rust.

Mechanical and chemical Mechanical and chemical forces break down rockforces break down rock

Just like the rock Just like the rock cycle weathering cycle weathering can take hundreds, can take hundreds, thousands, or thousands, or millions of years. millions of years.

The surface of the The surface of the earth will weather earth will weather at a faster rate at a faster rate because of the because of the exposure to air and exposure to air and water.water.

Mechanical and chemical Mechanical and chemical forces break down rockforces break down rock

Different rocks break Different rocks break down at different rates down at different rates such as limestone and such as limestone and granite. granite.

Climate can also affect Climate can also affect chemical weathering. chemical weathering.

Weathering occurs Weathering occurs faster in hot wet faster in hot wet regions than cold dry regions than cold dry regions. Why?regions. Why?

Mechanical and chemical Mechanical and chemical forces break down rockforces break down rock

Although mechanical weathering can Although mechanical weathering can occur more in cold regions rather occur more in cold regions rather than hot. Why?than hot. Why?