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Mechanical and chemical forces break down rocks
Transcript of Mechanical and chemical forces break down rocks
Weathering break rocks into smaller pieces.
Chemical weathering changes the mineral composition of rocks.
Weathering occurs at different rates.
Weathering is the process by which natural forces break down rocks. There are two types:
1. When a rock is physically broken apart.
Weathering is not the same for all rocks. Factors such as:
Surface area: The more of a rock is exposed, the faster it will break down.
Rock composition: Different kinds of rocks break down at different rates.
Climate: Weather is needed for chemical weathering to occur, and heat speeds up chemical weathering. It occurs faster in hot, wet regions than in cold, dry regions.
Is the breakdown of rocks by chemical reactions that change the rock's makeup or composition.
Dissolving: water is the main cause of chemical weathering. Air pollution also wears rocks.
Rusting: Oxygen in the air is also involved. Common minerals contain iron. When these minerals dissolve in water, oxygen in the air combines and produces rust.
2. When a chemical reaction changes the makeup of a rock.
Mechanical weathering produces physical changes in rocks.
Mechanical weathering is the breaking up of rocks by physical forces. In this process, rocks split apart but do not change in composition.
1. Ice Wedging: When water freezes in the cracks and pores of rocks, the force of it expansion split rocks apart.
2. Pressure release: Earth's forces can push rocks underground to the surface. This causes the rock to expand leading to exfoliation: rock gradually breaking off.
3. Plant root growth: Trees, bushes, and other plants crack the rocks.
4. Abrasion: Process of wearing down by friction. Water wears down rocks on riverbeds.