Exogenic Processes PDF

EXOGENIC PROCESSES  Learning Objectives: 1. Explain how weathering, erosion and deposition occur. 2. I d e n t i f y a g e n t s o f weathering, erosion and deposition.  A series of processes that create and transform the types of rocks in Earth’s crust. EXOGENIC PROCESSES A...

EXOGENIC PROCESSES  Learning Objectives: 1. Explain how weathering, erosion and deposition occur. 2. I d e n t i f y a g e n t s o f weathering, erosion and deposition.  A series of processes that create and transform the types of rocks in Earth’s crust. EXOGENIC PROCESSES Are processes that take place at or near the Earth’s surface that makes the surface wear away. It is very destructive, they are responsible for degradation and sculpting the Earth’s surface.  TYPES OF EXOGENIC PROCESSES Weathering Erosion Mass Movement (Mass Wasting) Deposition Sedimentation  WEATHERING refers to the process of disintegration (physical) and decomposition (chemical) of rocks. TYPES OF WEATHERING  A t y p e o f weathering in which rocks are physically broken into smaller pieces without a change in its composition. A physical change includes change in size and shape PHYSICAL WEATHERING  FACTORS THAT CAN CAUSE PHYSICAL WEATHERING 1. THERMAL AND PRESSURE CHANGE – Rocks crumble and break into fragments because they are subjected to alternating hot and cold temperatures many times. – When a rock gets hot, it expands (an increase in volume. While at night, the rocks her cold causing contraction (a decrease in volume). HEAT AND PRESSURE  FACTORS THAT CAN CAUSE PHYSICAL WEATHERING 2. TEMPERATURE – Rocks expand and are fractured when expose to high temperature. However, if the temperature drops to 0°C (freezing point of water), it also expands and causes fracture. TEMPERATURE  FACTORS THAT CAN CAUSE PHYSICAL WEATHERING 4. FROST WEDGING – Rocks have fracture in its surface and when water accumulates in the crack and at that point freezes, the ice expands and breaks the rocks apart. FROST WEDGING  FACTORS THAT CAN CAUSE PHYSICAL WEATHERING 5. ABRASION – The breakdown of rocks is caused by impact and friction. This primarily occurs during collision of rocks, sand and silt due to current or waves along a stream or seashore causing sharp edges and corners to wear off and become rounded  FACTORS THAT CAN CAUSE PHYSICAL WEATHERING 6. ORGANIC ACITIVITY – The roots grow causing penetration into the crack, expand and in the long run, break the rock.  FACTORS THAT CAN CAUSE PHYSICAL WEATHERING 7. HUMAN ACTIVITIES – Activities such as digging, quarrying, denuding forests and cultivating land contribute to physical weathering.  FACTORS THAT CAN CAUSE PHYSICAL WEATHERING 8. BURROWING ANIMALS – Animals like rats, rabbits and squirrels excavate into the ground to create a space for habitation. FACTORS THAT CAN CAUSE PHYSICAL WEATHERING  Decomposes rocks through chemical reactions that change the original rock-forming minerals.  FACTORS THAT CAN CAUSE CHEMICAL WEATHERING 1. DISSOLUTION – Rocks or minerals are dissolved in water.  FACTORS THAT CAN CAUSE CHEMICAL WEATHERING 2. HYDROLYSIS – Breaking down of rocks by acidic water to produce clay and soluble salt. Rock-forming minerals like amphibole, pyroxene and feldspar react with water and form different kinds of clay minerals.  FACTORS THAT CAN CAUSE CHEMICAL WEATHERING 2. CARBONATION – Process where carbon dioxide may bond with other substances. – A mixture of water and carbon dioxide is called carbonic acid. – Two examples of c a r b o n a t i o n weathering are The Limestone Pavement and The Stalactites CARBONATION  FACTORS THAT CAN CAUSE CHEMICAL WEATHERING 3. OXIDATION – Breaking down of rocks by oxygen and water, often giving iron-rick rocks a rusty-colored weathered surface. It is the responses of oxygen with minerals. If the iron oxidizes, the mineral in rocks decomposes. Rusting is an example of this chemical reaction. FACTORS THAT CAN CAUSE CHEMICAL WEATHERING  EROSION The movement of rock particles get carried away by wind, water, ice and gravity AGENTS OF EROSION WATER WIND ICE GRAVITY  TRANSPORT BY THE WATER 1. RUNNING WATER – It is the most force or agent of erosion. Waves constantly crash against shores, they pound rocks into pebbles and reduce pebbles to sand. Water sometimes takes sand away from beaches. – When there is heavy rain, rain, rock pieces are carried downstream to a suited depositional environment with the action of gravity. RUNNING WATER Water can carry almost any size of rocks. The greater the volume of water and the steeper the slope, the bigger and more rocks can be transported. Rock materials are loosened by heavy rains and strong winds and they can come speeding down slopes, sweeping in its path. TRANSPORT BY THE WATER  TRANSPORT BY THE WIND 1. WIND – It carries dust, sand, and volcanic ash from one place to another. Wind can sometimes blow sand into towering dunes. – This is common in dry areas such as deserts. – Wind transport can result in stunning landscapes as sand is blown away and creates sand dunes. – It create sandstorms that contain dust particles and deposit them in wide areas. TRANSPORT BY THE WIND  TRANSPORT BY THE ICE 1. ICE – Erosion by ice can erode the land. In frigid areas and on some mountaintops, glaciers move slowly downhill and across the land. As they move, they pick up everything in their path from tiny grains of sand to huge boulders TRANSPORT BY THE ICE WEATHERING VS. EROSION MASS MOVEMENT Slope movement Bulk movements of soil, sand and rock debris downslopes in response to the force of gravity or the gradual sinking of the Ea r t h ’ s g r o u n d su r f a c e i n a vertical direction. Examples: fall, slide, avalanche and flow. The term “mass wasting” was limited only to the variety of processes by which large masses of crustal materials are moved by the action of gravity from one place to another.  CLASSIFICATIONS OF MASS WASTING SLUMP SOLIFLUCTION EARTHFLOW MUDFLOW DEBRIS SLIDE DEBRIS FLOW ROCK FALL SOIL CREEP  SLUMP It is a type of mass wasting that result s in sliding of c o h e r e n t materials along a c u r v e d surface.  SOLIFLUCTION T h e s l o w downhill flow of soil  EARTHFLOW A downslope viscous flow of fine-grained materials that have been saturated with water and moves under the pull of gravity.  MUDFLOW It occurs when mud travels down slope very quickly.  DEBRIS SLIDE A type of slide characterized by the chaotic mov e m e n t o f rocks, soil and debris mixed with water and ice.  DEBRIS FLOW A moving mass of loose mud, sand, soil, rock, water and air that travels down a slope under the influence.  ROCK FLOW It occurs when pieces of rock break loose from a steep rock face or cliff.  SOIL CREEP A slow, gradual mov e m e n t o f soil or regolith downhill over time.  SOIL CREEP A slow, gradual mov e m e n t o f soil or regolith downhill over time.  DEPOSITION The process in which the weathered materials carried out by erosion settle down in a particular location.