Weathering and Erosion (2024) PDF

Weathering, Erosion, Mass Wasting GEOL 100 Landforms  Lesson Outline 01 Weathering -What is Weathering -Weathering Factors -Types of Weathering GEOGL 100 E...

Weathering, Erosion, Mass Wasting GEOL 100 Landforms  Lesson Outline 01 Weathering -What is Weathering -Weathering Factors -Types of Weathering GEOGL 100 Erosion -What is Erosion -Four Types of Erosion -Erosion by Water Mass Wasting -Types of Mass Wasting  02 Learning Outcomes Learn about weathering, its factors and 1. types. GEOL 100 2. Learn about erosion and its types. 3. Learn about mass wasting and its types.  03 WEATHERING -it is combined actions off all processes that cause rock to disintegrate physically or decompose chemically. -on the Earth's surface, it describes the breakdown or dissolution of rocks and minerals. GEOL 100 Weathering Process -agents of weathering include water, ice, acids, salts, includes: plants, animals, and variations in temperature. Physical Weathering -breaks rock down into smaller and smaller pieces. Chemical Weathering -completely alters minerals in rocks; creates new mineral.  Weathering 04 Factors GEOL 100 CLIMATE TIME MINERALLY OF PARENT ROCK NUMBER OF FISSURES OPENING DEGREE OF SLOPES  TYPES OF 05 WEATHERING 1. Mechanical or Physical Weathering GEOL 100 -in this type of weathering, a large rock is disintegrated into smaller pieces of rocks. When rocks disintegrate or break up without experiencing any change in their chemical composition, it is known as mechanical weathering. -the main process in mechanical weathering is abrasion, a physical process by which rocks and clasts are reduced in size. Abrasion by ice, water, and wind processes loaded with sediments can have immense cutting power.  1. Freeze-Thaw 06 It occurs when rocks are porous (contain holes) or permeable (allow water to pass through). Water enters cracks in the rock. When temperatures drop, the water freezes and expands causing the crack to widen. The ice melts and Two types of water make its way deeper into the cracks. The process repeats itself until the rock splits entirely. Mechanical GEOL 100 1. Salt Wedging Weathering It happens when saltwater seeps into rocks and then evaporates on a hot sunny day. Salt crystals grow within cracks and pores in the rock, and the growth of these crystals can push grains apart, causing the rock to weaken and break.  TYPES OF 07 WEATHERING 2. Organic or Biological Weathering GEOL 100 -it is also called bioweathering or biological weathering, is the general name for biological processes of weathering that break down rocks. This includes the physical penetration and growth of roots and digging activities of animals (bioturbation), as well as the action of lichens and moss on various minerals. -it is the disintegration of rocks as a result of the action by living organisms.  TYPES OF 08 WEATHERING 3. Chemical Weathering Weathering GEOL 100 -also known as decomposition or decay, is the breakdown of rock by chemical mechanisms. -it happens when rocks are worn away by chemical change.  09 2. Hydrolysis Three types of -in the process of hydrolysis, a new solution (a mixture of two or more substances) is formed Chemical as chemicals in rock interact with water. In many rocks, for example, sodium minerals Weathering interact with water to form a saltwater solution. GEOL 100 1. Carbonation 3. Oxidation -process in which -chemical weathering carbon dioxide chemically works on rocks that contain reacts with rocks and minerals. Carbonation iron. weathering occurs when carbon dioxide gases -Rust is a compound created dissolve in water and by the interaction of oxygen react with the surface of and iron in the presence of a rock or mineral to form water. As rust expands, it an acid. weakens rock and helps break it apart.  10 EROSION -it is geological process in which earthen materials are worn away and transported by natural forces such as wind and water. GEOL 100 4 types of Erosion: Water Erosion Wind Erosion Ice Erosion Gravity Erosion  11 Erosion by Water -Liquid is the major agent of erosion on GEOL 100 Earth. Rain, rivers, floods, lakes and the ocean carry way bits of soil and sand and slowly wash away the sediment.(If the wind is dusty, or water or glacial ice is muddy, erosion is taking place. The brown color indicates that bits of rock and soil are suspended in the fluid (air or water) and being transported from one place to another. This transported material is called sediment.)  12 4 types of Water GEOL 100 Erosion SPLASH EROSION SHEET EROSION RILL EROSION GULLY EROSION  13 Erosion by Wind GEOL 100 -wind is powerful agent of erosion. Aeolian (wind- driven) processes constantly transport dust, sand, and ash from one place to another. Wind can sometimes blow sand into towering dunes. -In dry areas, windblown sand can blast against a rock with tremendous force, slowly wearing away the soft rock. It polishes rocks and cliffs until they are smooth—giving the stone a so-called “desert varnish.”  14 Erosion by Ice GEOL 100 -Ice, usually in the form of glaciers, can erode the earth and create dramatic landforms. In frigid areas and on some mountaintops, glaciers move slowly downhill and across the land. As they move, they transport everything in their path, from tiny grains of sand to huge boulders. -Eroded sediment called "moraine" is often visible on and around glaciers.  15 Erosion by Gravity GEOL 100 -better known as "Mass Movement" -it describes the movement of soil or rock due to the force of gravity. Gravity impacts erosion in direct ways like landslides, mudslides and slump. It can also impact erosion in indirect ways, by pulling rain to the Earth and forcing glaciers downhill.  16 MASS WASTING -the movement of rock and soil down slope under the influence of gravity. GEOL 100 6 types of Mass Wasting: Creep Slump Landslide Rockfall Debris Flow Avalanche  17 CREEP -the imperceptibly slow, steady, downward movement of slope-forming soil or rock. Movement is caused by shear stress sufficient GEOL 100 to produce permanent deformation, but too small to produce shear failure. -it is commonly seen as curved tree trunks -important to look for when buying real estate but not life threatening.  18 SLUMP - is a type of mass wasting that results in GEOL 100 the sliding of coherent rock materials along a curved surface. In a slump, a portion of the mountain moves down a short distance. -it is less dangerous because they need generally move slowly, but they can still do damage to human construction  19 LANDSLIDE - is the movement of rock, earth, or debris GEOL 100 down a sloped section of land. Landslides are caused by rain, earthquakes, volcanoes, or other factors that make the slope unstable - Landslides have three major causes: geology, morphology, and human activity.  20 ROCKFALL -it is a natural and dynamic geologic process involving the detachment and rapid downward movement of rock. GEOL 100 - it happens off of outcrops like cliffs and road cuts (natural rock cliffs are usually quite stable except in areas of rapid erosion, while man-mad cliffs or road cuts are very unstable) -a number of geologic processes set the stage for rockfalls, including glaciation, weathering, and bedrock fractures.  21 DEBRIS FLOW - it is defined as mass-wasting events in GEOL 100 which turbulence occurs throughout the mass. - Debris flows generally occur during periods of intense rainfall or rapid snowmelt and usually start on hillsides or mountains.  22 AVALANCHE - is an air-fluidized flow of snow and ice or GEOL 100 rock and soil debris downslope. - an avalanche is typically triggered when material on a slope breaks loose from its surroundings  23 Thank you! GEOL 100 "Wherever you go, no matter what the weather, always bring your own sunshine." -Anthony J. D'Angelo