Lesson 7 Exogenic Processes PDF

Exogenic Processes How would you explain the reshaping of the Earth’s surface? Exogenic Processes External processes that occur at or near the surface of the Earth Part of rock cycle Responsible for transforming rock into sediment Degradation process (we...

Exogenic Processes How would you explain the reshaping of the Earth’s surface? Exogenic Processes External processes that occur at or near the surface of the Earth Part of rock cycle Responsible for transforming rock into sediment Degradation process (weathering, mass wasting, erosion, and transportation) Aggradation (deposition) Degradation Processes: Weathering, Mass Wasting, Erosion and Transportation Aggradation Processes: Deposition Weathering The physical breakdown and/or chemical alteration of rocks at or near Earth’s surface Degradation process Does not involve movement of materials Two types Mechanical Weathering Breaking of large rocks into smaller fragments without changing the rock’s mineral composition. FROST WEDGING Water that enters through the cracks and empty space of rocks expands when it freezes. FROST WEDGING INSOLATION WEATHERING Thermal stress Results from the expansion and contraction of rocks caused by temperature changes. UNLOADING OR PRESSURE RELEASE Occurs when the overlying rock is eroded away, causing the outer rock layer to expand more than the layers underneath. The expansion may separate the outer rock from the rock body.  CHEMICAL WEATHERING Decomposes rocks through chemical change. OXIDATION Oxygen dissolved in water will oxidize some materials Reddish-brown rust OXIDATION HYDROLYSIS Water is the most important agent of chemical weathering. Minerals dissolve into ions and react with water to form clay minerals. CARBONATION AND SOLUTION Carbon dioxide dissolves in water to form carbonic acid and reacts with carbonate rocks to form a soluble product or calcium  BIOLOGICAL ACTION Some plants and animals may create chemical weathering by releasing chelating and, audifying compounds that react with some minerals in rocks. Mass Wasting The mass movement of rocks, soil, and regolith. A step that follows weathering. Degradation process Factors That Influence Mass Wasting Gravity Oversteepenin  Factors That Influence Mass Wasting 1.Gravity 2.Steepness of slope 3.Water content of slope material 4.Amount of vegetation on the slope Oversteepening Adding moisture Vegetation FALLS Rock fall - occur when pieces of rock or mass of rocks become dislodged and makes free-fall along a steep of cliff. FALLS Debris fall – similar to rock fall, except that involves a mixture of soil regolith, vegetation, and SLIDE Sudden fast movement of cohesive mass of soil, rock, or regolith. TWO TYPES OF SLIDE - Translational slides - Rotational slides 2009 Cordillera Landslides Cotabato, Philippines: large landslides from the series of earthquakes in October 2019 TRANSLATIONAL SLIDES Involve movement of a mass of materials along well-defined surface, such as bedding plane, foliation surface, or joint surface. ROTATIONAL SLIDES Occur when the descending materials move masse along a concave, upward curved surface TYPES OF LANDSLIDE FLOWS It may be slurry flows or granular flows. SLURRY FLOWS - consist of a mixture of rocks and/or regolith with 20% to 40% water. GRANULAR FLOWS – contain 0 to 20% water. 2006 Guinsaugon Mudflow New Bataan (Compostela Valley) debris flow Guinsaugon Debris Avalanche  Erosion Degradation process Process of transporting weathered sediments by agents of erosion to different places. Agents: 1. Water 2. Glacier 3. Wind SPLASH EROSION (WATER) Raindrops cause tiny particles of soil to be detached and to move out RILL EROSION (WATER) Rainfall break apart the soil structure which moves down the slope as water flows overland as sheet GULLY EROSION (WATER) After heavy rain, water flows in narrow channels, eroding gullies into great depth. VALLEY EROSION (WATER) Continuous flow alongside land and move downward, which deepens a valley. BANK EROSION (WATER) Continuous flow of water wears out stones along the bank of streams and rivers. COASTLINE EROSION (WATER) Waves from ocean and seas crash against the shore, pounding the rocks into pebbles and reducing the pebbles to sand. Sand is also removed from the beaches, which changes the coastline. GLACIER Thick large mass of ice formed hundred or thousand of years mostly in remote areas like in the poles or in high mountains They move very slowly They are capable of great erosion They can erode land through plucking and abrasion GLACIER GLACIER PLUCKING It is the process wherein fractured bedrocks are incorporated into the ice. ABRASION It happens when the ice and its load of rock fragments slide over a bedrock. ABRASION PLUCKING AND ABRASION  WIND Formed by differences in pressure due to differential heating of the atmosphere by the sun. Carries dust, sand, and volcanic ash from one place to another In dry areas, strong wind wears away soft rocks, and also polishes rocks and cliffs until they are smooth WIND WIND  Transportation Materials are transported in four (4) distinct ways: ⮚Solution - Materials are dissolved in water and carried along by water. ⮚Suspension – suspended materials carried by medium (air, water, or ice) ⮚Traction – particles move by rolling, sliding, and shuffling along eroded surface. ⮚Saltation – particles move from the surface to the medium in quick repeated cycles. The TRANSPORTATION Deposition The process of weathering, mass wasting, erosion, and deposition are responsible for the continued reshaping of Earth’s surface. DEPOSITION is the aggradation or accumulation of weathered sediments to create different landforms. Spits Deltas Alluvia l fans Moraine s Sand dunes