Exogenic Processes PDF

EXOGENIC PROCESSES  EXOGENIC PROCESSES Process that takes place at or near the Earth’s surface that makes the surface wear away. Exogenic process are very destructive, they are responsible for degradation and sculpting the Earth’s surface.  EXOGENIC PROCESSES...

EXOGENIC PROCESSES  EXOGENIC PROCESSES Process that takes place at or near the Earth’s surface that makes the surface wear away. Exogenic process are very destructive, they are responsible for degradation and sculpting the Earth’s surface.  EXOGENIC PROCESSES I II III IV MASS WEATHERING EROSION DEPOSITION WASTING  EXOGENIC PROCESSES I Weathering is the WEATHERING physical disintegration or chemical alteration of rocks at or near the Earth’s surface.  PHYSICAL CHEMICAL BIOLOGICAL WEATHERING WEATHERING WEATHERING Is the Rocks break Rocks are broken disintegration or down as their down into smaller decay of rocks minerals change pieces without and minerals in composition changing their caused by (they become composition chemical or different (doesn’t change physical agents of substances) what they’re organisms. made of)  TYPES OF PHYSICAL WEATHERING  Exfoliation - soil and rock is removed (glaciers or uplifting), exposing rock found deep underground. - This releases the pressure causing the surface of the rock to expand and eventually crack.  Ice wedging/Frost action – Water enters small cracks in the rock – When it freezes, it expands and forces the crack to open more – The process repeats over again until the rock breaks apart  Temperature Changes - Daily (diurnal) and seasonal temperature changes affect certain minerals and facilitates the mechanical weathering of bedrock. - Warmer temperatures may cause some minerals to expand, and cooler temperatures cause them to contract. - This gradual expansion and contraction of mineral grains weakens the rock causing it to break apart into smaller fragments or to fracture. - This process is more common in desert climates because they experience extreme fluctuations in daily temperature changes. - Temperature changes are often not the dominant form of weathering, but instead temperature changes tend to accelerate other forms of weathering already occurring.  Salt Wedging - 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. - Similar process to frost wedging. - Most effective in coastal environments and semi-arid environments.  Abrasion - Occurs when material being transported wears away at a surface over time. - Gravity causes abrasion as a rock tumbles down a mountainside or cliff. - Moving water causes abrasion as particles in the water collide and bump against one another. - Strong winds carrying pieces of sand can sandblast surfaces. - Ice in glaciers carries many bits and pieces of rock. Rocks embedded at the bottom of the glacier scrape against the rocks below. TYPES OF CHEMICAL WEATHERING HYDROLYSIS HYDRATION OXIDATION CARBONATION Hydrolysis - A new solution (a mixture of two or more substances) is formed as chemicals in rock interact with water. - In many rocks, for example, sodium minerals interact with water to form a saltwater solution. Hydration - A form of chemical weathering in which the chemical bonds of the mineral are changed as it interacts with water. - One instance of hydration occurs as the mineral anhydrite reacts with groundwater. The water transforms anhydrite into gypsum, one of the most common minerals on Earth. Oxidation - Occurs when oxygen combines with another substance and creates compounds called oxides. - Rust, for example, is iron oxide. - This process occurs fast with water. Carbonation - Mixing of water with carbon dioxide to make carbonic acid. - This type of weathering is important in the formation of caves. - Dissolved carbon dioxide in rainwater or in moist air forms carbonic acid, and this acid reacts with minerals in rocks.  TYPES OF BIOLOGICAL WEATHERING Roots Of Plants - Some trees grow inside of rocks, which aids in biological weathering. - Roots of plants and trees delve into the soil in quest of moisture and nutrients. ANIMAL - The joints or cracks in the rocks are MICROBIAL BURROWING traversed by the roots as they ACTIVITY move through the soil, gradually rupturing the rock. - Additionally, larger, expanding roots may exert pressure on surrounding rocks. - Additionally, some plant roots release organic acids that aid in the dissolution of rock minerals  TYPES OF BIOLOGICAL WEATHERING Microbial Activity - Small creatures including bacteria, moss, lichens, and algae create organic acids. - This modifies the rock’s ANIMAL ROOTS OF PLANTS chemical makeup and BURROWING gradually erodes its outer covering. - Chelation: organisms such as lichen and moss produce acids that breakdown rocks.  TYPES OF BIOLOGICAL WEATHERING Animal Burrowing - Some creatures, including moles, squirrels, and rabbits, can cause fissures MICROBIAL in rocks. ROOTS OF PLANTS ACTIVITY - However, by making a fissure, these organisms absorb the nutrients from the rock. It progressively separates the rock into substantial pieces.  EXOGENIC PROCESSES II Removal of surface material from Earth’s crust, primarily soil and rock debris, and the transportation of EROSION the eroded materials by natural agencies from the point of removal.  AGENTS OF EROSION WATER Liquid water is the major agent of erosion on Earth. Rain, rivers, floods, lakes, and the ocean carry away bits of soil and sand and slowly wash away the sediment.  AGENTS OF EROSION ICE 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. Rocks carried by glaciers scrape against the ground below, eroding both the ground and the rocks. In this way, glaciers grind up rocks and scrape away the soil.  AGENTS OF EROSION WIND Wind is a powerful agent of erosion. Aeolian (wind-driven) processes constantly transport dust, sand, and ash from one place to another.  AGENTS OF EROSION GRAVITY Gravity pull all things toward Earth’s center. The result of these “creeps” or “avalanches” will be mixed piles of sediments usually below slumps in the land.  EXOGENIC PROCESSES III Is a rapid form of erosion that works primarily under the MASS influence of gravity in WASTING combination with other erosional agents.  CLASSIFICATION OF MASS WASTING ROCK FALLS It occurs when rock becomes dislodged because its change in potential energy becomes too great to maintain, and the potential energy becomes kinetic energy which cause the rock fragment to fall, restoring equilibrium.  CLASSIFICATION OF MASS WASTING LANDSLIDES Landslides are mass wasting events where large amounts of weathered rock materials slide down a hillslope or mountain side primarily by gravity – related erosion.  CLASSIFICATION OF MASS WASTING DEBRIS AND MUDFLOW Are mass wasting events that form when heavy rainfalls produce large amounts of runoff that transport eroded soils, sediments and plant debris down slope where the flows eventually spread out across valley bottoms.  CLASSIFICATION OF MASS WASTING SLUMP Fairly common form of mass wasting were the rock or soil collapses, breaks off from the hill slope, rotates slightly and slumps downhill.  CLASSIFICATION OF MASS WASTING CREEP It is the slowest mass wasting process that involves a very gradual downhill movement of soil, bedrock, and weathered rock fragments. Usually, the entire slope is slowly creeping downhill as a complete unit.  EXOGENIC PROCESSES IV Laying down of sediment that has been transported by an erosional agent. It occurs after DEPOSITION erosion. This process adds sediments, soil and rocks to a landform or land mass.