Earth's Materials and Processes (Lesson 8) PDF

EARTH’S MATERIALS AND PROCESSES EXOGENIC PROCESSES Exogenic processes are responsible for shaping the Earth’s surface and forming the geologic features that are seen on the surface of the Earth. come from forces ON OR ABOVE the Earth's surface  WEATHERING...

EARTH’S MATERIALS AND PROCESSES EXOGENIC PROCESSES Exogenic processes are responsible for shaping the Earth’s surface and forming the geologic features that are seen on the surface of the Earth. come from forces ON OR ABOVE the Earth's surface  WEATHERING A EROSION B MASS WASTING C SEDIMENTATION D WEATHERING WEATHERING the process by which rocks break into smaller pieces whether physically (disintegration) or chemically (decomposition).  TYPES OF WEATHERING MECHANICAL WEATHERING the breakdown of rock into smaller pieces by physical means. (ice, wind, water, gravity, plants, animals). There is no change in chemical composition of rocks. EXAMPLES OF MECHANICAL WEATHERING FROST WEDGING- a process in which water freezes in a crack of a rock and then the expansion edges the rock apart EXAMPLES OF MECHANICAL WEATHERING PRESSURE-RELEASE- a process wherein tectonic forces lift deeply buried rocks close to the surface and then erosion removes overlying rock, removing the pressure and causing rock to expand and fracture EXAMPLES OF MECHANICAL WEATHERING ABRASION- a process that consists of grinding and rounding of rock surfaces by friction and impact caused by waves and glaciers. EXAMPLES OF MECHANICAL WEATHERING ORGANIC ACTIVITY- a process in which a crack in a rock is expanded by plant roots or broke by animals and human activities. EXAMPLES OF MECHANICAL WEATHERING THERMAL EXPANSION AND CONTRACTION- occurs when temperature changes rapidly, causing the surface of the rock to heat or cool CHEMICAL WEATHERING the process by which rocks break down as a result of chemical reactions. It decomposes rocks through a chemical change in its minerals. CHEMICAL WEATHERING Some of its causes are oxidation, leaching, hydration, and carbonation. EXAMPLES OF CHEMICAL WEATHERING a. DISSOLUTION - a process in which a mineral or rock dissolves in water forming a solution like halite (rock salt) dissolved in water. EXAMPLES OF CHEMICAL WEATHERING b. HYDROLYSIS - a process in which a mineral reacts with water to form a new mineral that has water as part of its crystal structure like feldspar to clay. EXAMPLES OF CHEMICAL WEATHERING c. OXIDATION - a process in which a mineral decomposes when it reacts with oxygen like the rusting of iron. EROSION EROSION Erosion is the process of transporting weathered sediment by agents of erosion and to different places. Weathered materials are removed from the original site and transported away by natural agents. AGENTS OF EROSION  Running water is considered as the major and universal agent of soil erosion.  Other causes are gravity, human activities and animals. AGENTS OF EROSION  Running water is considered as the major and universal agent of soil erosion.  Other causes are gravity, human activities and animals. TYPES OF EROSION DUE TO GLACIERS GLACIERS- large, moving ice that can erode land in two ways: a. Plucking As glacier flows over a fractured bedrock surface, it loosens and lifts blocks of rock and incorporates them into the ice. b. Abrasion As the ices and its load of rock fragments slide over the bedrock, they function like sandpaper to polish and smoothen the surface below. MASS WASTING MASS WASTING Mass wasting is the mass movement of rocks and soil. It is the step that follows weathering. The driving force of mass wasting is gravity. Mass wasting is triggered and controlled by the following factors: a. Water- When the pores in sediments become filled with water, the cohesion among particles is destroyed, allowing them to slide past one another with relative ease. It also adds weight to a mass of water causing the material to slide or move downslope. Mass wasting is triggered and controlled by the following factors: b. Over Steepened Slopes- triggers movements of unconsolidated granular materials. It produces unstable slopes and mass movements in cohesive soils, regolith and bedrock. Mass wasting is triggered and controlled by the following factors: c. Vegetation removal- Plants protect against erosion and contribute to the stability of slopes because their root systems binds soil and regolith together. When plants are removed or lacking, mass wasting is enhanced, especially if slopes are steep and water is plentiful. Mass wasting is triggered and controlled by the following factors: d. Earthquakes- An earthquake and its aftershocks can dislodge enormous volumes of rocks and unconsolidated materials. SEDIMENTATION The process of separating small particles and sediments in water. This process happens naturally when water is still because gravity will pull the heavier sediments down to form a sludge layer.