Earth Science Handouts PDF

Earth Science Lesson 1 Endogenic and Exogenic Processes ENDOGENIC PROCESS An internal geomorphic process. The energy emanating from within the earth is the main force behind endogenic geomorphic processes. It involves geologic activities suc...

Earth Science Lesson 1 Endogenic and Exogenic Processes ENDOGENIC PROCESS An internal geomorphic process. The energy emanating from within the earth is the main force behind endogenic geomorphic processes. It involves geologic activities such as tectonic movements, metamorphism, seismic activities and magmatism. Mafic magma is less viscous than silicic (felsic) magma Primordial heat- the residual (leftover) heat from because it is hotter and contains less silica accretion and bombardment of the Earth during its early stages of formation. EARTHQUAKE Radioactive heat- the heat generated by long-term A weak to violent shaking of the ground produced by radioactive decay brought about by the disintegration the sudden movement of rock materials below the of natural radioactive elements. earth's surface. VOLCANISM The surface where the blocks of the Earth suddenly The eruption of molten rock (magma) onto the slip is called the fault or fault plane. surface of the planet. The intensity of the eruption depends on: Composition Viscosity of the magma and rise speed Interaction with external water MAGMATISM Formation and movement of magma. Magma - is the molten or semi-molten rock beneath the surface of the Earth. This molten state, when solidifies creates igneous rocks. Why do magma rise? Magma is less dense than the surrounding country rock. At deeper levels, magma passes through mineral grain boundaries and cracks in the surrounding rock. When enough mass and buoyancy is attained, the overlying surrounding rock is pushed aside as the magma rises. At shallower levels, magma may no longer rise because its density is almost the same as that of the country rock. The magma starts to accumulate and slowly solidifies. When the magma solidifies at depth, it can form different types of plutonic bodies. Viscosity A measure of a fluid’s resistance to flow. Magmas with low viscosity flow and erupt more easily than those with high viscosity. Temperature, silica content, and volatile content control the viscosity of magma. EXOGENIC PROCESS Occur on or near the surface of the Earth. These processes are usually influenced or driven by gravity, water, wind and organisms. WEATHERING Weathering is the breakdown of rocks into small pieces or transformation of rocks into a different substance. PHYSICAL WEATHERING Mechanical or physical weathering is the breakdown of rocks into pieces without any change in its composition. CHEMICAL WEATHERING Chemical weathering is brought about the reaction between the rocks and/or its minerals reacts with chemical agents that causes the rock to form substances that have different chemical properties from the original rocks Stalagmites and stalactites are some of the best known cave formations. They are icicle-shaped deposits that form when water dissolves overlying limestone then re-deposits calcium carbonate along the ceilings or floors of underlying caves.  MASS WASTING - Mass Wasting or Mass Movement refers to the large mass of earth materials being moved by gravity along a slope. Types of mass wasting: rock and debris falls, landslides, and flows. EROSION - Erosion is the transportation of weathered rocks. It is the removal of sediments from their source area. It is carried out by the same flowing agents causing rock physical weathering: wind, water, and ice. DEPOSITION - Deposition is the process in which the weathered materials carried out by erosion settle down in a particular location. TYPES OF DIFFERENTIAL STRESS Tensional stress- involves forces pulling in opposite directions Strain: Stretches and thins the rock Associated plate boundary type: Divergent Stretching and thinning Lesson 2 Compressional stress - involves forces pushing together Strain: Rock folding and thickening DEFORMATION OF EARTH’S CRUST Associated plate boundary type: Convergent DEFORMATION Deformation is the process by which the crust is deformed along tectonic plate margins. Deformations produces a variety of a geological features which includes folds, faults, foliations and joints. Folding Geological features are recognizable, mappable rock unit in a region being mapped by geologists. Shear stress - involves transverse forces; FORCES OF DEFORMATION Strain: opposing blocks or regions of material moving past each other. STRESS - Stress is the force exerted per unit Associated plate boundary type: Transform area. STRAIN - Strain results in the form of deformation of the rock caused by the stress. Strain in rocks can be represented as a change in rock volume and/or rock shape, as well as fracturing the rock. Shearing Faulting  PRODUCTS OF DEFORMATION: GEOLOGICAL STRUCTURES FOLDS AND FAULTS Fault – A fault is a fracture in bedrock along which rocks on side have moved relative to the other side. DIP-SLIP FAULTS Strike-slip fault - Normal faults - move a fault on which by a vertical motion the two blocks where the hanging-wall slide past one moves downward another. Shear relative to the footwall stress creates along the dip of the strike-slip fault fault. Normal faults are created by tensional forces in the crust. Reverse fault - occurs when the “hanging wall” moves up or is thrust over the “foot wall” Compressional stress creates reverse fault Geologic folds are layers of rock that are curved or bent by ductile deformation. Folds are most commonly formed by compressional forces at depth, where hotter temperatures and higher confining pressures allow ductile deformation to occur. TYPES OF FOLDING Anticline - upward bend Anticlines are arch-like, or A-shaped, folds that are Monocline convex-upward in shape. Oil geologists are interested in bend with horizontal ends. anticlines because they can form oil traps. Monoclines are step-like folds, in which flat rocks are upwarped or downwarped, then continue flat. Syncline - downward bend Synclines are trough-like, or U shaped, folds that are concave-upward in shape.  The Wilson Cycle - Explains the process of the opening (beginning) and the closing (end) of an ocean. Seafloor spreading Seafloor spreading - A geologic process where there is a gradual addition of new oceanic crust in the ocean floor through a volcanic activity while moving the older rocks away from the mid-oceanic ridge. Proposed by an American geophysicist,Harry H. Hess in 1960. By the use of the sonar, Hess was able to map the ocean floor and discovered the mid-Atlantic ridge (mid- ocean ridge). The Subduction Process The highly dense oceanic crust that is formed after a progressive spreading is destined to two possible occurrences: It can either be subducted into the ocean deep trench Continue to spread across the ocean until it reaches a coast.