Chapter 5 weathering and soil

Decomposition

Decomposition is the process of changing once-living material into dark colored organic matter

How is a leaf organic matter?

Organic natter is the remains of something dead , and overtime, roots die and leaves and twigs fall to the ground. organisms living in the soil decompose these materials for food

Define biota

All of the organisms that live in a region are known as biota

The chemical and physical processes that change things overtime are called .

Weathering

Define mechanical weathering

When physical processes naturally break rocks into smaller pieces, mechanical weathering occurs

Oxidation

A process that causes chemical weathering is called oxidation

What kind of rocks weather most rapidly

Soft rocks

What conditions produce the fastest weathering

Hot and wet

Compare and contrast information about weathering

Chemical: changes chemical makeup of rocks both: changes over time mechanical: breaks up rocks into smaller pieces

Cause: ice wedging or frost wedging

Effect: water collects in the cracks of a rock and freezes.the frozen water widens the cracks. Repeated thawing and freezing breaks the rocks apart

Cause:abrasion

Effect:friction or impact grinds away rock.

Cause : plants

Plants grow in the cracks, their roots grow wider and longer, breaking apart the rock

Cause: animals

Effects: Animals dig holes in the soil around the rock. This allows water to enter the soil-which looses

And erodes the rock.

Mechanical weathering breaks rocks into ones

Large; smaller

The smaller rocks have than the one larger rock

More surface area

Rock material with can hold more water and nutrients for plants

More Scarface area; water and nutrients

water minerals in rock

Dissolves

Normal rain is what pH and causes some ________

5.6 pH; chemical weathering

Acid rain has a pH of ________ and is caused by ________ in air reacting with rain water

4.5 or less; pollutions

Acid rain causes much more chemical weathering than ________

Normal rain

Acid rain = pH below ___ ; normal rain = pH of ____

5.5; 4.5

Oxidation combines ________ with other elements or molecules.

Oxygen

Oxidation forms as a _________ on the _________ surface

Layer; outside