this is a reviewer on cie 114 - geology for civil engineers subject, Summaries of Geology

Download this is a reviewer on cie 114 - geology for civil engineers subject and more Summaries Geology in PDF only on Docsity! CIE 114: Geology for Engineers THE COMPOSITION AND STRUCTURE OF THE EARTH Geology - the study of the solid earth. Main Branches Allied Branches - Physical Geology - Engineering Geology - Mineralogy - Mining Geology - Petrology - Geophysics - Structural Geology - Geohydrology - Stratigraphy - Geochemistry - Economical Geology Physical Geology - Deals with physical features of the earth, natural phenomena like landslides, earthquakes, and weathering. Mineralogy Study of minerals. Petrology Study of rocks. Structural Geology - Deals with deformations, dislocations, and disturbances under the influence of tectonic forces. Stratigraphy - Study of Earth’s history. Economical Geology - Deals with economic minerals like talc, graphite, mica, asbestos, and others. HISTORY OF EARTH 299 million years ago - (At the start of the Permian Period of geological time), Pangea (Pangaea) existed. 100 million years before - It began to break up. 1915 - The concept of Pangea was first developed by German meteorologist and geophysicist Alfred Wegener. Continental drift - Large-scale horizontal movements of continents. - Relative to the ocean basins during one or more episodes of geologic time. ANATOMY OF THE EARTH Crust - It consists of oceanic and continental crust. - outermost solid part of the earth - thin layer of the earth - total thickness normally between 30-50 km - It forms 0.5-1.0 percent of the earth’s volume and less than1 percent of earth’s mass. Mantle - It contains 83 percent of the total volume of the earth. - 68 percent of the total mass of the earth - Its thickness ranges from 10-200 km. Core - volume and mass of core are 16% - 32% of the total volume and mass of the earth respectively - outer core is liquid while the inner core is solid ▪ Conorod Discontinuity - between upper and lower crust ▪ Mohorovicic Discontinuity (Moho or M discontinuity) - separates the crust from the mantle - its average depth being about 35 km ▪ Repiti Discontinuity - between the upper and lower mantle ▪ Gutenberg Discontinuity - lies between the mantle and the outer core - below 2900 km from earth’s surface ▪ Lehman Discontinuity - between inner and outer core PLATE TECTONICS Plate Tectonics is the study of the movement of these rigid shell parts (or plates). 7 Major Tectonic Plates 1. African Plate 2. Antarctic Plate 3. Eurasian Plate 4. Indo-Australian Plate 5. North American Plate 6. South American Plate 7. Pacific Plate Manmade slope - infrastructure projects - embankments, earth dams, road cuttings etc. Types of Slope Protection Geosynthetics - man-made materials used to improve soil conditions - ex. separation, strengthening, filtration, drainage or liquid barrier Gabions - a cage, cylinder or box filled with rocks, concrete or sand and soil - capable of withstanding significant movements from undercutting or land slipping Retaining Wall - to resist soil lateral pressure or hold back soil material Sheet Piles - built to retain earth, water or any other filling materials Riprap - continuous ground cover stone - resistant to erosion - used to slow the structured runoff velocity - used to stabilize unstable slopes owing to infiltration Reinforced Concrete - achieved by combining the concrete and steel MODULE #4 Weathering - process of decay, disintegration, decomposition of rocks Mechanical Weathering - also called physical weathering and disaggregation (causes rocks to crumble) - caused by frost, ice, plant roots, running water and sun heat Disintegration - process of breaking up of rocks into small pieces Decomposition - process of breaking up of mineral constituents to form new components Denudation - when the surface of the earth is worn away by the chemical - lower layers are exposed Main types of physical weathering Thermal Expansion - expansion of minerals due to temperature fluctuations - fluctuations cause small cracks in the rocks Frost Weathering - also known as ice wedging - processes including freeze-thaw, frost wedging and frost shattering Exfoliation and Pressure Release - rocks that peel away from the stripped rocks - disintegrating rocks into smaller fragments along the fractures - it occurs when rocks parallel to the land surface break up Abrasion - when rocks and sediments grind against each other - causing wind and water rushing over rocks Salt Weathering - also known as haloclasty or salt crystal growth - process of saline solutions entering the cracks in a rock Plant and Animal Activities - animals that burrow in the ground - breaking up soil and loosen rocks Chemical Weathering - decomposition of rocks due to chemical reaction between the minerals in rocks and the environment - caused by water, oxygen, acids and living organisms Main types of chemical weathering Hydrolysis - occurs when water dissolves minerals in a rock Oxidation - ex. Rust formation - occurs when oxygen reacts with iron to form iron oxide (rust) Solution Weathering - acid rain Living Organisms - performing chemical reactions to obtain minerals from soil and rocks Erosion - earthen materials are worn away - transported by natural forces Liquid Water - major agent of erosion on earth - liquid habitats carry away bits of soil and sand - causes slowly and washing away the sediment Rainfall produces for types of soil erosions - splash erosion - sheet erosion - rill erosion - gully erosion Wind - powerful agent of erosion - processes that transport dust, sand and ash from one place to another Ice - formed by glaciers - can erode the earth - transporting from tiny granules of sand to huge boulders Zoogenic Erosion and anthropogenic erosion - caused by animals and humans