Exogenic Processes PDF

EXOGENIC PROCESSES The Earth’s surface is constantly changing. There are processes involved in sculpting the Earth’s surface, such as weathering, mass wasting, erosion, transportation, and deposition.  1. Describe how rocks undergo...

EXOGENIC PROCESSES The Earth’s surface is constantly changing. There are processes involved in sculpting the Earth’s surface, such as weathering, mass wasting, erosion, transportation, and deposition.  1. Describe how rocks undergo weathering. 2. Explain how the products of weathering are carried by erosion and deposited elsewhere. 3. Make a report on how rocks and soil move down slope due to the direct action of gravity. 4. Describe the Philippine soil. 5. Devise ways to facilitate own Learning learning. Competencies: 6. Display scientific values and attitudes. Contoso 2 S u i t e s Large Image Slide WHAT IS EXOGENIC PROCESS?  Exogenic Process – these are processes that take place at or near surface, that makes the surface wear away.  Endogenic Process – are geodynamic processes (seismic activities)  Include degradation and aggradation processes. Contoso 3 S u i t e s Large Image Slide WHAT IS EXOGENIC PROCESS?  Degradation:  Weathering  Mass wasting  Transportation  Erosion  Aggradation:  Deposition Contoso 4 S u i t e s Contoso 5 S u i t e s WEATHERING  The physical breakdown and/or chemical alteration of rocks at or near the Earth’s surface is referred to as weathering.  Weathering can be mechanical or chemical.  Mechanical weathering or disintegration is the breaking up of large rocks into smaller fragments without changing the rock’s mineral composition.  Chemical weathering decomposes rocks through chemical change. Contoso 6 S u i t e s FROST WEDGING/FROST WEATHERING Occurs in regions where temperature fluctuates above and below freezing point. Water that enters through rock’s MECHANICAL spaces expands when it freezes. WEATHERING When ice thaws, water can flow further into the cracks. Repeated freeze-thaw cycle weakens the rock. Contoso 7 S u i t e s FROST WEDGING/FROST WEATHERING MECHANICAL WEATHERING Contoso 8 S u i t e s FROST WEDGING/FROST WEATHERING MECHANICAL WEATHERING Contoso 9 S u i t e s THERMAL STRESS/INSOLATION WEATHERING Results from the expansion and contraction of rocks caused by temperature changes. The outer surface of the rocks is often warmer or colder than the MECHANICAL inner portions. WEATHERING The process of peeling off is called exfoliation. Note: warmer in warmer regions, cooler in cooler regions Contoso 10 S u i t e s PRESSURE RELEASE/UNLOADING Occurs when the overlying rock is eroded away, causing the outer rock layer to expand more than the layer underneath. This expansion may separate MECHANICAL the outer rock from the rock WEATHERING body. The exfoliation due to pressure release is often called sheeting. Unloading is evident in intrusive igneous rocks. Contoso 11 S u i t e s Ocean waves Organic activity Animals that dig holes on the ground and exposed rocks. Anthropogenic activities MECHANICAL become the primary cause of weathering like road WEATHERING construction, mining or even a simple walking. Weeds and plants roots can grow in cracks. Contoso 12 S u i t e s OXIDATION Oxygen dissolved in water will oxidize some minerals. Lose of Electron is Oxidation (LEO) CHEMICAL Fe²→Fe³+e- Iron-rich minerals are prone to WEATHERING oxidation. Reddish-brown rust will appear on the surface which easily crumbs and weakens the rock. Contoso 13 S u i t e s OXIDATION CHEMICAL WEATHERING Contoso 14 S u i t e s HYDROLYSIS Affects carbonate minerals Hydro – water, lysis – to dissolve The new mineral appears to be chalky. CHEMICAL WEATHERING Contoso 15 S u i t e s CARBONATION Carbon dioxide dissolved in rainwater creates carbonic acid. Carbonic acid reacts with calcium carbonate which forms calcium bicarbonate. CHEMICAL WEATHERING Contoso 16 S u i t e s BIOLOGICAL ACTION CHEMICAL WEATHERING Contoso 17 S u i t e s MASS WASTING  movement of rocks, soil, and regolith  A step that follows weathering  Driving force: gravity Contoso 18 S u i t e s ROCK AND DEBRIS FALL Rock fall occur when a piece of rock or mass of rock becomes dislodged and makes free-fall TYPES OF along steep cliff. Debris fall involves a mixture of MASS soil and vegetation WASTING Contoso 19 S u i t e s ROCK AND DEBRIS FALL TYPES OF MASS WASTING Contoso 20 S u i t e s  cohesive mass of soil, rock, or regolith Caused by failure Two types: translational slides and rotational slides Translational slides – movement of a mass of materials along a well-defined TYPES OF surface such as bedding plane, foliation surface, or joint surface. MASS Rotational slides or slumps – WASTING occur when the descending materials move along a concave, upward curved surface. Contoso 21 S u i t e s LANDSLIDES TYPES OF MASS WASTING Contoso 22 S u i t e s Materials behave as a liquid Commonly occur in humid areas Classification according to composition: slurry flows and granular flows Slurry flows – composed of a mixture of rocks/or regolith with TYPES OF 20% to 40% water. Granular flows – contain 0 to MASS 20% water WASTING Contoso 23 S u i t e s  Solifluction flow – moves at around 1 cm/yr and occurs in areas saturated with water.  Debris flows – move at around 1 m/yr to 100 m/h; these result from heavy rains  Mudflows – high velocity TYPES OF mixtures of sediments and MASS water. The velocities are greater than 1 km/h; these WASTING result from heavy rain and can travel long distances. Contoso 24 S u i t e s  of regolith down a slope, as observed in bent trees and fences  Earthflows – have velocities that range from less than 1 cm/yr to less than 100 m/h  Grain flows – have velocities that range from 9 to 100 m/h TYPES OF to less than 100 km/h; they are relatively dry material MASS like sand dunes. WASTING  Debris avalanche – very high velocity flows (more than 100 km/h) of large volume of mixtures of rocks and regolith Contoso 25 S u i t e s Mass wasting is a natural process. Removal of vegetation HUMAN AND Oversteepening of slope MASS Addition of moisture WASTING Contoso 26 S u i t e s EROSION  Transforming materials (sediments) from place to place by its agents  Forces: water, wind, ice  Opposite of deposition Contoso 27 S u i t e s Water: primary agent of erosion Wind: carries dust, sand, and AGENTS OF ash from one place to another EROSION Ice: mostly in the form of glacier Contoso 28 S u i t e s Splash erosion – raindrops cause tiny particles of soil to be detached and to move out. TYPES OF WATER EROSION Contoso 29 S u i t e s Sheet erosion – raindrops break apart the soil structure which moves down the slope as water flows overland as sheet. TYPES OF WATER EROSION Contoso 30 S u i t e s Gully erosion – after heavy rain, water flows in narrow channels, eroding gullies into great depth. TYPES OF WATER EROSION Contoso 31 S u i t e s Valley erosion – continuous water flow alongside land and move downward, which deepens a valley. TYPES OF WATER EROSION Contoso 32 S u i t e s Bank erosion – continuous flow of water wears out stones along the bank of streams and rivers. TYPES OF WATER EROSION Contoso 33 S u i t e s Coastline erosion – waves from the 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. TYPES OF WATER EROSION Contoso 34 S u i t e s Seaside cliff erosion – the striking of ocean waves erodes seaside cliffs, forming hales that create caves. Continuous pounding of waves may create an arch that may fall, leaving nothing but rock columns called sea stocks. TYPES OF WATER EROSION Contoso 35 S u i t e s Seaside cliff erosion TYPES OF WATER EROSION Contoso 36 S u i t e s Wind carries dust, sand, and ash from one place to another; polishes rocks and cliffs. Most common in deserts and beaches. Affected by land condition. Causes sand dunes and EROSION BY ventifacts. WIND Can be damaging Contoso 37 S u i t e s Can erode land through:  Plucking: fractured bedrocks are incorporated into the ice. Removal of entire chunks of rock.  Abrasion: happens when ice and its load of rock fragments slide over a bedrock. Involves EROSION BY scratching the bedrock with debris in the basal ice. ICE Glaciers carriers moraine. Contoso 38 S u i t e s Climate Topography FACTORS Vegetation IMPACTING Tectonic Activity EROSION Contoso 39 S u i t e s distinct ways: Solution – materials are dissolved in water and carried along by water. Suspension – the suspended particles are carried by a medium (air, water or ice) Traction – particles may be TRANSPORTATIO rolling, sliding, and shuffling N along eroded surface movements occurs in all erosional agents. Saltation – particles move from the surface to the medium in quick repeated cycles. Contoso 40 S u i t e s  Deposition – the process in which the weathered materials carried out by erosion settle down in a particular location. DEPOSITION Contoso 41 S u i t e s HOW DELTAS ARE FORMED Deltas – are formed when a river loses energy as it flows to an area of slow moving water, such as lake or sea. WATER AND LANDFORMS Contoso 42 S u i t e s  FORMED Alluvial Fans – are formed when a stream reaches a flat area called piedmont or gently sloping plain. WATER AND LANDFORMS Contoso 43 S u i t e s FLOOD PLAINS AND LEVEES Flood plain – a flat wide expanse of alluvium covering flat areas prone to flooding. They are formed when silts are deposited on flat surface during flood. Levees – when a river overflows its bank, its velocity decreases, WATER AND leaving coarse sediments deposited to form a small, LANDFORMS natural embankment alongside the channel. Contoso 44 S u i t e s FLOOD PLAINS AND LEVEES WATER AND LANDFORMS Contoso 45 S u i t e s  Glacial till – formed when all unsorted deposits of rock formed directly by the ice Moraines – are layers or ridges of till. A long pile of rocky material at the edge of a glacier is called lateral moraine, while at the middle of the glacier is called medial moraine. They are landforms composed of glacial till deposited primarily by glacial ice. GLACIER AND LANDFORMS Contoso 46 S u i t e s  Esker – a winding ridge of sand and gravel deposited by glaciers,  Drumlins – a streamlined asymmetrical hills composed of till.  Kames – are steep-sided hills. - or knob, is a glacial landform, an irregularly shaped hill or mound composed of sand and gravel and till that accumulates in a depression on a retreating glacier. GLACIER AND LANDFORMS Contoso 47 S u i t e s GLACIER AND LANDFORMS Contoso 48 S u i t e s GLACIER AND LANDFORMS Contoso 49 S u i t e s Loess – the accumulated blanket of silt carried by wind in suspension and deposited over broad areas. WIND AND LANDFORMS Contoso 50 S u i t e s materials in the shape of hills or ridges. Dunes are formed in deserts or above low-lying coasts where sand is constantly renewed by onshore winds flowing across the sandy beaches. WIND AND LANDFORMS Contoso 51 S u i t e s  Thank You ROCEL GONZALES MISLANG [email protected] Customize this Template Template Editing Instruct ions and Feedback Contoso 53 S u i t e s