NOTES Weathering.notebook May 17, 2016

Transcription

1 Weathering, Erosion and Deposition Weathering, Erosion and Deposition physical Weathering: The ( ) or smaller of rock into particles. mechanical breakdown transportation Erosion: The or movement of the weathered sediments. settling Deposition: The of the weathered sediments. Weathering Two types of weathering Physical 1. ( ) Chemical 2. Mechanical Any process that causes a rock to crack or WITHOUT break into pieces ly changing the rock. Frost Water seeps into small cracks in a rock. As the water it. Over time, the cycle of and freezing Wedging freezes will cause the rock to split break or apart. melting expands 1

2 Root Trees and can grow roots through cracks in rocks and break Wedging plants them apart over time. hairlike roots Even the of mosses can grow between the grains that make up the rock. Exfoliation Result of extreme changes. heated temperature As rock is by the sun, the expands outside of the rock. When temperatures cool at night, the outside of the rock. The cycle of heating and cooling causes the outer layers of the rock to off layers in. contracts break ("peel") Abrasion ( action) This process occurs when streams grinding sediments wind carried by or collide blown sand cause particles to into each other and any other surrounding rock. 2

3 Any process that causes rocks to by action resulting in a change of the rock s composition mineral. breakdown Carbonation carbon dioxide Occurs when in the atmosphere dissolves in the droplets of water that make up clouds. carbonic This forms a weak acid that reacts with certain rocks that contain calcite the mineral. These rocks include and limestone. marble Carbonic acid rain water seeps into the limestone bedrock through the cracks. The reaction limestone dissolves the. CaCO 3 + H 2 CO 3 Ca HCO 3 (calcium carbonate) (Calcium bicarbonate) (carbonic acid) Karst topography caves This process forms underground 3

4 NOTES Weathering.notebook 4

5 Hydration water Occurs when dissolves certain minerals in a rock. Water Example: will dissolve much of the feldspar in granite allowing it to break apart. The quartz remains behind to become sand. Oxidation oxygen Occurs when in the atmosphere combines with certain minerals to change their form and breakdown rock. Plant Plants Acids produce weak acids that can also dissolve certain minerals that make up rocks. Human Activity Gases produced by humans can dissolve in water acid rain droplets of clouds to produce. sulfur dioxide nitrogen oxides sulfuric acid nitric acid is the factor that affects the rate of weathering. Chemical In warm climates, is the dominant type of weathering. Weathering Physical Weathering Climate Temperature major frost In cold climates, frost action wedging action (also known as ) is the dominant type of weathering. 5

6 Precipitation As precipitation increases, the amount (and rate) of frost action increase will. Chemical weathering is the most rapid in warm wet/humid, climates. As precipitation increases, the amount (and rate) of increase weathering will. What type of weathering would be more common in a warm and dry climate... Physical (or) Chemical? Desert = wind abrasion... rock Different types Differential weathering is the process by which softer, less rocks wear away, leaving harder, more rocks behind. (their mineral composition) weather-resistant resistant May 14 7:31 AM 6

7 Which rock is more resistant to weathering? Particle size Weathering occurs on the surface of rocks. So the more that is exposed to weathering, the the rock will be broken down. surface outside faster area As the rock breaks down into smaller pieces, surface area the more is increases exposed and the rate of weathering Quick Review Climate 1. Different rock types (mineral comp.) 2. Particle size 3. ** smaller particles = fastering weathering Soil Soil is a combination of organic weathered matter rock and (as a result Soil Layers (Soil Profile) of biological activity). Humus is decayed plant and animal material found in soil. Soil that contains rich humus is considered soil. ~25% 7

8 Soil Layers (Soil Profile) Due to biological activity Darker, richer, topsoil is a result of biological activity 8