APPLIED GEOLOGY

                                                 EINSTEIN COLLEGE OF ENGINEERING

 DEPT OF CIVIL ENG.  

GEINSTEIN COLLEGE OF ENGINEERING DEPT OF CIVIL ENGG Internal Processes  Processes that produce magmas, volcanoes, earthquakes and build mountain ranges.Energy comes from the interior of the Earth, Most from radioactive decay - nuclearenergy. Principle of Uniformitarianism  Processes that are operating during the present are the same processes that have operatedin the past. i.e. the present is the key to the past. If we look at processes that occur today,we can infer that the same processes operated in the past.  Problems: Rates -- rates of processes may change over time for example a river might deposit 1 mmof sediment /yr if we look at it today. but, a storm could produce higher runoff and carrymore sediment tomorrow. Another example: the internal heat of the Earth may have beengreater in the past than in the present -- rates of processes that depend on the amount of heat available may have changed through time.Observations -- we may not have observed in human history all possible processes.Examples: Mt. St. Helens, Size of earthquakes.Perhaps a better way of stating the  Principle of Uniform itarianism is that the laws of nature have not changed through time. Thus, if we understand the physical and chemicallaws of nature, these should govern all processes that have taken place in the past, aretaking place in the present, and will take place in the future. Energy  All processes that act on or within the Earth require energy. Energy can exist in manydifferent forms: Gravitational Energy -- Energy released when an object falls from higher elevations tolower elevations.  Heat Energy -- Energy exhibited by moving atoms, the more heat energy an object has,the higher its temperature. Chemical Energy -- Energy released by breaking or forming chemical bonds.  Radiant Energy -- Energy carried by electromagnetic waves (light). Most of the Sun'senergy reaches the Earth in this form.   EINSTEIN COLLEGE OF ENGINEERING DEPT OF CIVIL ENGGEINSTEIN COLLEGE OF ENGINEERING DEPT OF CIVIL ENGG  Atomic Energy -- Energy stored or released in binding atoms together. Most of the energygenerated within the Earth comes from this source. Heat Transfer Heat Moves through material by the following modes:   Conduction - atoms vibrate against each other and these vibrations move from hightemperature areas (rapid vibrations) to low temperature areas (slower vibrations).

- Heatfrom Earth's interior moves through the solid crust by this mode of heat transfer.   Convection - Heat moves with the material, thus the material must be able to move. Themantle of the Earth appears to transfer heat by this method, and heat is transferred in theatmosphere by this mode.  Radiation - Heat moves with electromagnetic radiation (light) Heat from the Sun or froma fire is transferred by this mode Geothermal Gradient  Temperature and pressure increase with depth in the Earth. Near the surface of the Earththe rate of increase in temperature (called the Geothermal Gradient ) ranges from 15 to35oC per kilometer. Temperature at the center of the Earth is about 4500oC The Earth -- What is it? The Earth has a radius of about 6371 km, although it is about 22 km larger at equatorthan at poles. Internal Structure of the Earth :Density, (mass/volume),
 Temperature, and Pressure increase with depth in the Earth. Compositional Layering Crust - variable thickness and compositionContinental 10 - 50 km thick Oceanic 8 - 10 km thick   Mantle - 3488 km thick, made up of a rock called peridotite Core - 2883 km radius, made up of Iron (Fe) and small amount of Nickel (Ni)   EINSTEIN COLLEGE OF ENGINEERING DEPT OF CIVIL ENGGEINSTEIN COLLEGE OF ENGINEERING DEPT OF CIVIL ENGG Layers of Differing Physical Propertie s  Lithosphere -
 about 100 km thick  (deeper beneath continents)  Asthenosphere - about 250 km thick to depth of 350 km - solid rock, but soft andflows easily.  Mesosphere - about 2500 km thick, solid rock, but still capable of flowing. Outer Core - 2250 km thick, Fe and Ni, liquid  Inner core - 1230 km radius, Fe and Ni, solidAll of the above is known from the way seismic (earthquake waves) pass through theEarth as we will discuss later in the course.
 Surface Features of the Earth Oceans cover 71 % of Earth's surface -- average depth 3.7 km. Land covers remainingsurface with average of 0.8 km above sea levelOcean Basins Continental Shelf, Slope, and rise    Abyssal PlainsOceanic ridgesOceanic Trenches Plate Tectonics Tectonics = movement and deformation of the crust, incorporates older theory of continental drift.