CE 212 Geology for Civil Engineering Review Guide PDF

GeoloGy for CIVIl eNGINeerING (Ce 212) WEEKS 1-8 ********************************************************************* WeeK 1-2 1 - Geology as a Discipline...

GeoloGy for CIVIl eNGINeerING (Ce 212) WEEKS 1-8 ********************************************************************* WeeK 1-2 1 - Geology as a Discipline 2 - Importance of Geology to the Field of Civil Engineering 3 - The Earth and the Earth’s Systems  GEOLOGY one of the most tactile snd hands-on interdisciplinary field which studies the earth;s physical structure  2 Main Branches of Geology: 1) Physical Geology - concerned with the work of natural processes which bring about changes upon the earth’s surface 2) Historical Geology -study of earth’s geologic past  Earth’s entire history is divided into 4 MAJOR DIVISIONS named in ‘abstract time’ 1) Eon - largest division 2) Era: Precambrian Time (oldest)-Paleozoic-Mesozoic-Cenozoic (youngest era) 3) Period 4) Epoch - smallest division  Geologic Time Scale: a standard timeline and important tool to portray the history of the earth  EXTERNAL STRUCTURE of the EARTH: Spheres of the Earth 1) Atmosphere - layer above the lithosphere and hydrosphere a. Troposphere - lowest layer of the atmosphere b. Stratosphere c. Mesosphere d. Thermosphere e. Exosphere 2) Biosphere - the ecosphere; also known as the ‘zone of life’ 3) Cryosphere - contains huge quantities of ice at the poles and elsewhere 4) Geosphere/Lithosphere - also known as ‘land’ 5) Hydrosphere - the layer of water surrounding the lithosphere  INTERNAL STRUCTURE of the EARTH 1) Crust 2) Mantle 3) Core - Inner; Outer  Discontinuities in the Earth’s layers 1) Conrad Discontinuity - separates the upper and lower crust 2) Mohorovicic Discontinuity - the transition zone between the crust and the mantle 3) Repetti Discontinuity - separates the upper mantle from the lower mantle  Theories: Uniformitarianism vs Catastrophism Uniformitarianism (James Hutton)  “The Present is the Key to the Past”  assumes that the chemical and physical laws of nature have not changed throught Earth’s geologic past/history  also called Theory of Gradualism Charles Lyell successfully challenged the principle of catastrophism Catastrophism (Baron Georges Cuvier) *********************************************************** WeeK 3 4 - Plate Tectonics  CONTINENTAL DRIFT THEORY sought to explain how continents shift position on Earth's surface set forth in 1912 by German Meteorologist, Alfred Wegener  SEA FLOOR SPREADING the process where the oceanic ridges spreads and moves away from the ridge axis with a motion like that of a conveyor belt as new lithosphere is created occurs at DIVERGENT PLATE boundaries helps explain continental drift in the theory of plate tectonics creates NEW CRUST  CRUSTS 1) continental crust  the layer of igneous, sedimentary and metamorphic rocks (mostlygranite)   forms the continents and the areas of shallow seabed close to the shore (CONTINENTAL SHELVES)  Lighter than oceanic crust 2) oceanic crust  uppermost layer of the oceanic portion of a TECTONIC PLATE (mostly basalt)  Denser than continental crust  MID-OCEAN RIDGE large mountain ranges rising from the ocean floor where SEA FLOOR SPREADING occurs 1) Mid-Atlantic Ridge  separates the North American plate from the Eurasian plates  separates the South American plate from the African plate 2) East Pacific Rise  separates the Pacific plate from the North American plate, the Cocos plate, the Nazca plate, and the Antarctic plate 3) Southeast Indian Ridge  marks where the southern Indo-Australian plate forms a divergent boundary with the Antarctic plate.  SUBDUCTION destroys OLD CRUST occurs at CONVERGENT PLATE boundaries another part of PLATE TECTONICS occurs at SUBDUCTION ZONES, when tectonic plates crash into each other instead of spreading apart  SUBDUCTION ZONES zones where edge of denser plates subducts/slides’goes down under the lighter or less dense one  HOT SPOTS spots where magma from the mantle concentrates and is capable of breaking through the Earth’s surface DO NOT MOVE...the continental plate above them moves builds an archipelago…volcano arcs as it goes  PLATE TECTONICS a SCIENTIFIC THEORY describing the large-scale motion of nine (9) large plates and the movements of a larger number of smaller plates of Earth's lithosphere explains the features and movement of Earth's surface in the present and the past  3 FORCES as MAIN DRIVERS of Tectonic Plates 1) Ridge push 2) Mantle Convection Currents  ALFRED WEGENER German geophysicist and meteorologist credited as the first to develop a THEORY OF PLATE TECTONICS, a modern version of the Continental Drift  ASTHENOSPHERE the plastic-like layer of Earth below the lithosphere on which tectonic plates (lithospheric plates) float  TECTONIC PLATES also called lithospheric plate is a massive, irregularly shaped slab of solid rock, generally composed of both 1) continental lithosphere/crust 2) oceanic lithosphere//crust  9 MAJOR TECTONIC PLATES 1) Pacific Plate - largest plate 2) Antarctic Plate - 2nd largest plate 3) South American Plate 4) North American Plate 5) African Plate 6) Eurasian Plate 7) Indian Plate 8) Indo-Australian Plate 9) Australian Plate  PANGAEA - supercontinent which later broke up in the Jurassic period  EVIDENCES that support PLATE TECTONICS  continents fit together almost like puzzle pieces forming Pangaea  similar fossils and rock units on different continents  occurrence of earthquakes  continental and ocean floor features including mountains, volcanoes, faults, and trenches  PLATE BOUNDARIES 1) Divergent Plate boundary - plates rip or move apart (e.g., Baja, California) 2) Convergent Plate boundary - one plate dives (“subducts”) beneath the other, resulting in a variety of earthquakes and a line of volcanoes on the overriding plate (e.g., Taal Volcano) a) Continental-Continental collision (C-C) b) Oceanic-Continental (O-C) c) Oceanic-Oceanic (O-O)  3) Transform Plate Boundary - where plates slide laterally past one another in opposite directions (e.g., San Andreas Fault)  CONVERGENT boundaries occur where plates push together. Because the plates are pushing together, crust is either FOLDED or CRUNCHED at the boundary. When one plate SUBDUCTS or goes under the lighter plate, it is called SUBDUCTION.  When two CONTINENTAL plates meet, it is called continental-continental collision. Because both crusts have the same DENSITY neither plate will sink below the other. If the plates keep moving, their edges will eventually CRUMPLE and FOLD.. Sometimes, the folded crust pushes up to create MOUNTAINS.  When an oceanic plate sinks under another oceanic plate it is called OCEANIC-OCEANIC subduction. The OLDER plate sinks because it is COLDER and DENSER than the plate on top. As the it sinks into the asthenosphere, it MELTS, getting destroyed and reabsorbed into the mantle.  OCEAN TRENCH area that shows where the plate disappears and where subduction zones are found  OCEANIC PLATES pulling apart would result in: escaping magma to pile up and be extruded to the surface magma would cool and turn into igneous rocks mountains will be formed over a long period of time  CONTINENTAL PLATES colliding against each other would result in: Earthquakes Area of collision of both plates will be lifted to form mountains *********************************************************** WeeK 4 5 - Minerals 6 - Rocks and the Rock Cycle  MINERALS are essentially the building blocks of rocks; also called ‘NATIVE ELEMENTS’  HOW MINERALS are FORMED 1) crystallization from a solution - evaporation of a liquid solution 2) crystallization from magma 3) changes in heat and pressure  CHARACTERISTICS OF MINERALS 1) inorganic 2) naturally-occurring 3) solid 4) specific or definite chemical composition  5) crystalline structure  MINERAL GROUPS: Minerals are grouped by their chemical composition Minerals that form the rocks within Earth’s crust belong to 7 Main Mineral Groups/Examples: 1) Silicate - Quartz, Feldspar, Olivine, Mica 2) Oxide - Hematite, Magnetite, Corundum 3) Sulfate - Gypsum, Barite, Anhydrite 4) Sulfide - Galena, Pyrite, Bornite 5) Carbonate - Calcite, Dolomite, Malachite, Azurite 6) Native elements - Silver (Ag), Copper (Cu), Gold (Au) 7) Halides - Halite (NaCl)  PHYSICAL PROPERTIES OF MINERALS 1) Color  best described by using primary or simple colors, with descriptors and subsidiary colors added as necessary  least useful property when identifying minerals 2) Streak  color of a mineral when powdered and observed against an unglazed white porcelain plate (streak plate) 3) Hardness  a measure of the mineral’s resistance to scratching  FRIEDRICH MOHS - Austrian mineralogist who devised a scale based on one mineral's ability to scratch another (1822)  1 (softest mineral-TALC), and 10 (hardest-DIAMOND) 4) Cleavage or Fracture CLEAVAGE: describes how minerals break along certain plains of weakness in their crystal structure How easily the cleavage is obtained: a) Perfect b) Good c) Imperfect Direction of the cleavage surfaces: a) Cubic cleaves in 3 directions @ 90o to one another b) Rhombohedral cleaves in 3 directions but not @ 90o to one another c) Octahedral cleaves in 4 directions d) Dodecahedral cleaves in 6 directions e) Basal cleaves in 1 direction  f) Prismatic cleaves in 2 directions FRACTURE: describes the quality of the cleavage surface; : It is the property of a mineral breaking in a more or less random pattern with no smooth planar surfaces a) Conchoidal - fracture surface is a smooth curve, bowl-shaped (common in glass); b) Hackly - fracture surface has sharp, jagged edges; c) Uneven - fracture surface is rough and irregular; d) Fibrous - fracture surface shows fibres or splinters 5) Crystalline Structure - arrangement of the atoms, molecules or ions that make up the crystal and how they are joined (crystal lattice) a) Microcrystalline structure: can only be viewed using high magnification b) Cryptocrystalline structures: can only be viewed using high magnification c) Amorphous : If there is no crystalline structure : there are very few amorphous crystals : can only be observed under extremely high magnification 6) Luster  the property of mineral that indicates how much the surface of a mineral reflects light  luster of a mineral is affected by the brilliance of the light used to observe the mineral surface  Terms to describe LUSTER: a) Metallic: the mineral is opaque and reflects light as a metal would b) Sub-metallic: the mineral is opaque and dull; the mineral is dark-colored c) Non-metallic: the mineral does not reflect light like a metal; are described using modifiers that refer to commonly known qualities: i. Waxy: the mineral looks like paraffin or wax ii. Vitreous: the mineral looks like broken glass iii. Pearly: the mineral appears iridescent, like a pearl iv. Silky: the mineral looks fibrous, like silk v. Greasy: the mineral looks like oil on water vi. Resinous: the mineral looks like hardened tree sap (resin) vii. Adamantine: the mineral looks brilliant, like a diamond 7) Transparency or Diaphaneity - a mineral’s degree of transparency or ability to allow light to pass through it - depends on the thickness of the mineral 8) Tenacity - describes how the particles of a mineral hold together or resist separation 9) Magnetism - allows a mineral to attract or repel other magnetic material  10) Odor - most minerals have no odor unless they are acted upon in one of the following ways: moistened, heated, breathed upon or rubbed 11) Taste - only soluble minerals have a taste, but it is very important that minerals not be placed in the mouth or on the tongue 12) Specific Gravity - a comparison or ratio of the weight of the mineral to the weight of an equal amount of water  MOHS’ SCALE of HARDNESS ROCK CYCLE  ROCKS the materials that form the essential part of the Earth’s solid crust. hard mass of mineral matter comprising one or more rock-forming minerals are formed from the cooling and crystallization of molten material (magma/lava)  PETROLOGY the study of rocks (Greek: ‘petra’– rock; ‘logos’–science) deals with the description of rocks  PETROGENESIS the study of the origin of rocks  ROCK CYCLE links the 3 MAIN GROUPS or TYPES of ROCKS through processes of formation and transformation  3 MAIN GROUPS or TYPES of ROCKS 1) Igneous Rocks 2) Sedimentary Rocks 3) Metamorphic Rocks  PROCESSES involved in the ROCK CYCLE INTERNAL PROCESSES  1) Burial and compaction 2) Deformation and metamorphism (heat and pressure) 3) Uplift 4) Melting 5) Cooling 6) Crystallization of magma (solidification) EXTERNAL PROCESSES 1) WeatheringProcess a) weathering b) erosion c) transportatation d) deposition e) lithification: compaction and cementation 2) Hydrologic Cycle  The rock cycle is a never-ending cycle: it has no beginning and no end.  Rocks can change throughout many different processes through the rock cycle. *********************************************************** WeeK 5 7 - Igneous Rocks  MAGMA contains mixture of minerals, small amounts of dissolved gases (H20 vapor, CO2, Sulfur) high temp and pressure underneath the earth keeps magma in a FLUID state will either be erupted to the top or may cool in place causing crystals to form and eventually solidify  lighter SILICA-rich minerals > float tot the TOP  heavier SILICA-rich minerals > go to the bottom  PROPERTIES/CLASSIFICATION of MAGMA: 1) Temperature  difficult to measure due to danger and risks involved 2) Density  Controlled by MAGMA COMPOSITION a) Basaltic Magma – rich in Fe (Iron), hence its dark color b) Rhyolitic Magma – rich in Silica, hence it light color c) Andesitic Magma – falls in between  Controlled by TEMPERATURE & PRESSURE a) HIGH TEMP: melts EXPAND  b) LOW DENSITY & HIGH PRSSURE: melts COMPRESS 3) Volatile Content  H20: most abundant volatile in most magmas  CO2: next most abundant volatile 4) Viscosity (thickness)  resistance to FLOW (opposite of FLUID)  depends primarily on: a) MAGMA COMPOSITION  higher SILICA content: higher viscosity  lower SILICA content: lower viscosity b) TEMPERATURE: viscosity decreases with increasing temperature of magma  low TEMP: higher viscosity  higher TEMP: lower viscosity  viscosity (thickness) of the magma that erupts from a volcano affects the shape of the volcano  very viscous (thick) magma: volcanoes with STEEP slope  less viscous magma: FLATTER volcanoes  IGNEOUS ROCKS formed through cooling, solidification and consolidation of molten material within (magma) or on the surface of earth (lava)  BASES for CLASSIFICATION of IGNEOUS Rocks 1) Texture a) Aphanitic - fine-grained b) Phaneritic - coarse-grained c) Porphyritic - large crystals embedded in fine-grained matrix d) Pyroclastic - consolidation of volcanic fragments e) Vesicular - contain voids left by bubbles as magma solidifies f) Glassy - resembles dark manufactured rx 2) mineral composition  Feldspar is the most common mineral found in igneous rocks  Basalt is the most common igneous rock  Others: olivine, quartz, amphibole, pyroxene, and muscovite  INTRUSIVE versus EXTRUSIVE Plutonic Igneous Rx Classification Volcanic Mode of Origin (formed magma lava from) Inside the earth Where Earth’s surface Cools slowly Rate of Cooling Cools quickly/rapidly Medium to Large Size of Crystals/grains Small/ Fine Low Mineral content High Solidifies due to slow cooling Solidification process Solidifies due to exposure to air underneath the earth Examples  2 MAIN CATEGORIES of IGNEOUS ROCKS 1. Intrusive (Plutonic) Igneous Rocks  formed beneath the surface of the Earth’s crust, where magma COOLS SLOWLY, resulting in COARSE-GRAINED mineral grains 2. Extrusive (Volcanic) Igneous Rocks  formed on the surface of the earth as a result of volcanic activitywhere it COOLS and CRYSTALLIZES RAPIDLY, resulting in FINE-GRAINED mineral grains  ********************************************************** WeeK 6 8 - Volcanism  VOLCANOES an opening in the earth's surface where molten rock can escape are closely associated with PLATE TECTONIC activity can be active, dormant or extinct are powerful agents of change…they can create new landforms, but they can also destroy everything in their path The 2 types of plate boundaries that are most likely to produce volcanic activity: 1) divergent plate boundaries 2) convergent plate boundaries  TYPES of VOLCANOES 1) cinder cones, 2) composite volcanoes (stratovolcanoes), and 3) shield volcanoes 4) lava domes  Volcanoes can be categorized into several types based on:  shape,  eruption style, and  the materials they erupt  CATEGORIES of VOLCANIC ERUPTIONS 1. Effusive eruption - build up gently-sloping Shield volcanoes 2. Explosive eruption - build up more steeply-sloping Composite volcanoes  VOLCANIC ERUPTIONS 1) Icelandic - often build lava plateaus 2) Hawaiian - form shield volcanoes (quite large and have gentle slopes) 3) Strombolian - moderate bursts of expanding gases that eject clots of incandescent lava in cyclical or nearly continuous small eruptions 4) Vulcanian - forms dark, turbulent eruption clouds that rapidly ascend and expand in convoluted shapes 5) Pelean - associated with explosive outbursts that generate pyroclastic flows, dense mixtures of hot volcanic fragments and gas 6) Plinian - intensely violent kind of volcanic eruption  VOLCANIC HAZARDS 1) Tephra/ash 2) Lava Flows 3) Pyroclastic Density Currents 4) Pyroclastic Falls 5) Lahars - specific kind of mudflow made up of volcanic debris 6) Volcanic Gases 7) Volcanic landslides 8) Climate change  STEPS IN MITIGATING VOLCANIC HAZARDS: 1) understanding what a volcano can do 2) how volcanic hazards behave 3) what can be done to avoid them *********************************************************** WeeK 7 9 - Sedimentary Rocks  SEDIMENTARY ROCKS formed by the accumulation of sediments product of: 1. weathering of pre-existing rx 2. transport of the weathered products 3. deposition of the materials followed by LITHIFICATION: 4. compaction and 5. cementation of the sediment the only type of rock that may contain fossils, or evidence of life  3 Basic Types/Classification of Sedimentary Rocks 1) Clastic/Detrital sedimentary rocks - made from pieces of rock (called clasts) that have been mechanically weathered 2) Chemical sedimentary rocks - form from the inorganic precipitation of minerals from a fluid (chemical weathering) 3) Organic sedimentary rocks - form from the accumulation and lithification of organic debris, such as leaves, roots, and other plant or animal Material (biological weathering)  *********************************************************** WeeK 8 10 - Soil Formation; Weathering Products  WEATHERING the physical and chemical breakdown/disintegration) of rocks at or near the surface – exposed to wind, water, ice, acids, salt, living organisms (plants...animals) and temperature  3 TYPES of WEATHERING 1) Mechanical/Physical Weathering : disintegration 2) Chemical Weathering : decomposition 3) Biological Weathering : disintegration + decomposition  FACTORS that DIRECTLY INFLUENCE the RATE of WEATHERING 1) temperature 2) rock type 3) moisture availability  EROSION physical removal and transportation of weathered material by water, wind, ice, or gravity Mass wasting - also called gravitational erosion, is the transfer or movement of rock or soil down slope primarily by gravity 1) Fluvial Erosion (Water) 2) Aeolian Erosion(Wind) 3) Glacial and Periglacial Erosion (Ice) 4) Gravitational Erosion (Mass Wasting) a) Rock falls b) Landslides c) Debris/mud flows d) Slumps e) Creep  DEPOSITION process by which weathered and eroded materials are laid down or placed in a location that is different from their source  DEPOSITIONAL ENVIRONMENTS refers to the location where sediments are deposited (e.g., rivers, lakes, bottom of deep oceans…). greatly influences the characteristics of sedimentary rocks, including their lithology, minerals, texture, sedimentary structures, and fossils  KEYS to IDENTIFICATION of DEPOSITIONAL ENVIRONMENTS 1) Lithology - a combination of the mineral content and sedimentary texture of the rock 2) Sedimentary Structures - useful for determining which way was up in the original sequence of sediments especially if looking at beds of  sediment that have been tilted to high angles, far from their original horizontal position 3) Fossils - remains or traces of biological organisms preserved in rocks commonly found in sedimentary rocks  TYPES of DEPOSITIONAL ENVIRONMENTS 1) Continental/Terrestrial 2) Marginal Marine/Transitional 3) Marine  FACTORS affecting SOIL FORMATION (Nature of Soils and Rate of Soil Formation (CLORPT) 1) CL - climate 2) O - Organic Matter 3) R - Relief/Topography 4) P - Parent Materials 5) T - Time  SOIL PROPERTIES 1) Color 2) Structure 3) Texture  SOIL PROFILE GOOD LUCK, my dear students!!!