Weathering, Erosion & Deposition ESS 2015-16. Weathering The breaking up of rock into smaller pieces.

Presentation on theme: "Weathering, Erosion & Deposition ESS 2015-16. Weathering The breaking up of rock into smaller pieces."— Presentation transcript:

1 Weathering, Erosion & Deposition ESS 2015-16

2 Weathering The breaking up of rock into smaller pieces

3 Chemical Weathering Chemical weathering breaks down bonds holding the rocks together, thus they fall apart, forming smaller and smaller pieces.

4 Chemical Weathering More common where there is a lot of water. Water is important to many of the chemical reactions that can take place. More common where temperatures are warmer.

5 Chemical Weathering Most common types of chemical weathering Oxidation Hydrolysis Dissolution Plant acid Hydration

6 Oxidation Rocks containing metals are combined with oxygen to form “rusts”. The areas in these rocks that are oxidized are weaker & thus more susceptible to physical weathering.

7 Hydrolysis A reaction with water in which a molecule is cleaved into two parts by the addition of a molecule of water Affects silicate and carbonate minerals. Pure water ionizes & reacts with silicate minerals.

8 Hydrolysis Example Mg 2 SiO 4 + 4H + + 4OH - ⇌ 2Mg 2+ + 4OH - + H 4 SiO 4 Olivine (forsterite) + 4 ionized H 2 O molecules ⇌ ions in solution + silicic acid in solution Don’t need to write this

9 Dissolution Slightly acidic water dissolves rock. Carbonic acid Sulfuric Acid

10 Dissolution When carbonic acid is combined with a mineral like calcite (CaCO 3 ), calcium and bicarbonate ions are released and carried off by groundwater. CaCO 3 + H 2 CO 3  Ca +2 + 2 HCO -3 Don’t need to write this Marble & Limestone

11 Dissolution Sulfurous gas (volcanoes & factories) can dissolve in water to form sulfuric acid. Acid Rain SO 2 + H 2 O  H 2 SO 4

12 Plant Acid Mosses and lichens produce weak acids that dissolve the minerals that hold rocks together.

13 Hydration H+ and OH- ions attach to the atoms & molecules of a mineral. Increases volume within rock, creates stress & breaks rock down

14 Rates of weathering Factors : Amount of surface area exposed to chemical weathering Type of mineral Climate Especially warm & wet

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