Weathering, Erosion & Deposition Notes

Weathering •The process of breaking down rock on Earth’s surface•Rocks are broken down into smaller and smaller pieces and eventually help to create soil•2 types of weathering – mechanical and chemical•Mechanical Weathering – the process in which rock is physically broken into smaller pieces•Chemical Weathering – the process that breaks down rock through chemical changes Mechanical Weathering •There are 6 main types of mechanical weathering•Frost Wedging– water seeps into the cracks of rocks, freezes, and expands to break rocks apart•Root Wedging – plant roots grow larger and larger in the cracks of rocks and eventually break rocks apart•Salt Wedging – water seeps into the cracks of rocks and evaporates leaving salt behind; salt forms salt crystals over time that break rocks apart•Abrasion – rocks are broken down by moving particles carried by wind, water, ice, or gravity•Exfoliation – outer layers of rocks weather and peel off in thin sheets•Thermal Expansion – the heating and cooling of rocks due to environmental conditions throughout the year; constant expanding and contracting causes rocks to break over time Chemical Weathering •There are 4 main types of chemical weathering•Oxidation – occurs when oxygen dissolves in water and combines with minerals in rocks, reducing their resistance to weathering•Carbonation – the mixing of water with carbon dioxide to make carbonic acid•Hydrolysis – water reacts with rocks and changes the chemical composition of minerals, reducing their resistance to weathering•Dissolution – the process of rocks dissolving when exposed to rain water Weathering Examples •Acid rain breaking down limestone•Frost wedging splitting rocks apart•Tiny particles of sand wearing away rock layers by abrasion Erosion •The process by which water, ice, wind, or gravitymoves pieces of rock or soil•Rock or soil is moved to a new location•Sediment - small, solid pieces of material from rocks or organisms•3 processes that cause erosion – waves, moving water, and wind Mass Movement •Movements of large masses of rock, soil, or mud•Occurs along the sides of steep hills and mountains•There are 4 main types of mass movement – landslide, mudflow, slump, and creep Erosion Examples •Sand being moved by wind•A muddy river carrying sediment downstream•Waves removing sand from a beach Deposition •The process by which sediment settles and is deposited in a new location•Sediment is deposited by wind, water, and ice•Builds up new land on Earth’s surface•3 major landforms created by deposition – deltas, alluvial fans, and moraines•Delta – a landform of sediment deposited where a river flows into an ocean•Alluvial Fan – a deposit of sediment formed where a stream leaves a mountain range•Moraine – a mass of sediment carried down and deposited by a glacier Deposition Examples •A river delta forming as a river flows into an ocean•An alluvial fan forming at the base of a mountain stream•A glacier dropping rock and other debris to form a moraine Weathering, Erosion or Deposition? Read each scenario. Write “W” for weathering, “E” for erosion, or “D” for deposition. Rain washing away soil E Sediment settling at the bottom of the ocean D A glacier wearing down layers of rock W Powerful ocean waves breaking down rocks over time W Wind and water from a hurricane moving sediment E A sand dune forming in the desert D Mechanical Weathering Physical Frost Wedging Root Wedging Salt Wedging Abrasion Thermal Expansion Chemical Weathering Chemical Oxidation Carbonation Hydolysis What are the three processes that cause Erosion? water, wind, waves Sand, rivers, rock hurricanes, tornados, glaciers physical and chemical weathering How are deltas formed? sediment deposited where a river flows into an ocean deposit of sediment formed where a stream leaves a mountain range mass of sediment carried down and deposited by a glacier