Introduction Introduction Geology Ch Chapt apter 1 r 1 Geology - PDF document

Introduction Introduction Geology Ch Chapt apter 1 r 1 Geology is the study of the earth, a complex, integrated system of Understanding related parts, components, or sub- Earth systems that interact in an organized (Earth systems) fashion, affecting one another in various ways. A Dynamic and Evolving Planet Introduction Introduction Introduction Introduction The systems The interaction of these subsystems has of the earth resulted in a dynamically changing planet in which matter and energy are include the: continuously recycled into different forms. – Atmosphere – Biosphere – Hydrosphere – Lithosphere – Mantle (plate tectonics) – Core (geo- dynamo & geomagnetics) Earth Systems Earth Systems Earth Systems Earth Systems Climate system (how, why, etc) Plate Tectonics (theory/geological model) 1. Weather, complex, unable to predict with 1. Combines volcanism, earthquakes, shape accuracy beyond week or so of continents, seafloor surface, etc 2. Climate = weather over time, general 2. Driven by convection within earth mantle predictions, due to internal heat, radiation, 3. System driven by sun; interaction with 3. Affects lithosphere, crust & outer mantle ocean/land, atmosphere, earth rotation/tilt, (depth to 100 km) and asthenosphere etc, plus interference due pollution, (plastic layer within mantle) volcanic dust, etc (geology) 1

Earth Systems Earth Systems The plate tectonics system: how does : how does The plate tectonics system the heat energy inside the Earth move the heat energy inside the Earth move Plate Tectonic: and thus affect the crustal plates? and thus affect the crustal plates? Driving force similar to boiling pot of water Convection causes hot w ater to rise… ...w here it cools, m oves laterally, sinks,… Hot m atter from the …causing plates to m antle rises,… form and diverge. W here plates converge, a Plate Plate cooled plate is dragged under… …sinks, w arm s, …w arm s, and rises again. and rises again. What is geology? The geodynamo The geodynamo system system: rapid motion of : rapid motion of the liquid outer core stirs up electrical the liquid outer core stirs up electrical � Geology is the study of the Earth. flow in the solid (iron) inner core – – flow in the solid (iron) inner core causing Earth’ ’s magnetic field s magnetic field causing Earth � Physical geology is concerned with the materials and processes which compose and operate on the surface of, and within, Earth. � Historical geology is concerned with the origin and evolution of Earth's continents, oceans, atmosphere, and life. 2

Geology and the What is geology? Formulation of Theories Geologists are employed in � What is a theory? diverse occupations. � Principle occupations � It is arrived at through the scientific method, which include: involves � Mineral and � gathering and analyzing facts energy resource � formulating hypotheses to explain the phenomenon exploration � testing the hypotheses � and finally proposing a theory. � Solving � The hypotheses is a tentative explanation. environmental � A scientific theory is a testable explanation for some problems natural phenomenon, that is supported by a large body of evidence. � Predicting natural disasters Scientific method: Scientific method: Scientific method: Steps 1. Observation/Experimentation ->someone develops tentative explanation -> becomes hypothesis 2. Hypothesis -> presentation (publication or abstract/presentation verbally) to peers 3. Peers challenge hypothesis - If passes challenge then several hypotheses may form theory 4. Theory (-> presentation) - Challenge to theory 5. Scientific model (combine theories with hypotheses) How Does Geology Relate to the How Does Geology Relate to the The scientific method The scientific method Human Experience? Human Experience? in Geology in Geology • Geology pervades our everyday lives and is a part of many aspects of the goal: the goal: human experience, including the arts and is to explain how the universe works is to explain how the universe works literature. • The range of environmental problems and issues of concern to society require a basic understanding of geology. 3

Global Geologic and Environmental Global Geologic and Environmental How does geology affect our daily How does geology affect our daily Issues Facing Humankind Issues Facing Humankind lives? lives? • Most scientists would • Natural Events argue that • Economics and Politics overpopulation is the greatest problem • Our Role as Decision facing the world makers today. • Increasingly large • Consumers and Citizens numbers of people • Sustainable must be fed, housed, Development and clothed, with a minimal impact on the environment. Discussion: product source Global Geologic and Environmental Global Geologic and Environmental Origin of the Universe Origin of the Universe Issues Facing Humankind Issues Facing Humankind • Did it begin with a Big Bang? • The greenhouse effect is the retention of heat in the – In the Big Bang atmosphere, which results in an increase in the theory, the universe temperature of Earth’s surface and atmosphere, began approx. 14 thus producing global warming. billion years ago (13.7 Ga). – At that time an extremely compressed, dense, hot body of matter exploded, began to expand and is now cooling Origin of the Universe Origin of the Universe Origin of the Universe Origin of the Universe How do we know? Evidence for the How do we know? Evidence for the Big Bang: Big Bang: – Evidence: universe 1. Doppler effect is expanding from 2. Background Motion to left a central point. radiation: The causes waves 1. Doppler effect: red & blue shift to have shorter 1. Doppler effect: entire universe has wavelength on the spectral line a pervasive and left and longer on right (wavelengths of constant 2. Radiation so temperature is galaxy light) shifts background Example: 2.7 degrees above to red end (longer radiation, thought siren on car absolute zero ( -273.0 C) wavelength) due to be the faint moving to left is or -270.3 C higher pitch on the expansion of afterglow of the Big left and lower where it should be on right side galaxies. Bang. at absolute zero 4

Origin of Solar system Origin of Solar system Origin of Solar system Origin of Solar system Solar System: The nebular hypothesis (4.6 Solar System: The nebular hypothesis (4.6 Ga) Immanuel Kent, German 1755 ) Immanuel Kent, German 1755 Ga Summary Summary 1. 1. the sun forms (rotating cloud gas & dust, the sun forms (rotating cloud gas & dust, compact, ignite, fusion =>proto- compact, ignite, fusion =>proto -sun (early sun)) sun (early sun)) 2. the planets form the planets form 2. ● planetesimals ● planetesimals (hot gases cool to these, (hot gases cool to these, crash together to form terrestrial planets) crash together to form terrestrial planets) ● inner rocky planets (terrestrial) inner rocky planets (terrestrial) ● V, M, E, M V, M, E, M ● ● outer outer jovian jovian planets (gas & ice) planets (gas & ice) J, S, U, N J, S, U, N Origin of Solar system Origin of Solar system Origin of Solar system Origin of Solar system Origin of Solar system Origin of Solar system Origin of the solar system Origin of the solar system Small bodies of the solar system Small bodies of the solar system • • Asteroids (between Mars & Jupiter, Asteroids (between Mars & Jupiter, 300 with dia.>100km, 10,000 with 300 with dia.>100km, 10,000 with diameter>10km) diameter>10km) • • Meteorities Meteorities – – small pieces of asteroids, small pieces of asteroids, probably similar formation, left overs overs probably similar formation, left • • Comets Comets – – ice and dust, located in ice and dust, located in outer reaches of solar nebula outer reaches of solar nebula 5

Our Solar System Our Solar System Earth Its Origin and Evolution � Its Place in Our Solar System – The Solar System formed from a rotating cloud of interstellar matter about 4.6 billion years ago – This cloud, upon condensing, collapsed under the influence of gravity and flattened into a rotating disk. � Earth formed from a swirling eddy of nebular material 4.6 billion years ago, accreting as a solid – The sun, planets, and moons formed within this disk. body and soon thereafter differentiated into a layered planet during a period of internal heating. Why Earth is a Dynamic and Evolving Planet Why Earth is a Dynamic � Earth is composed of 3 concentric layers. and Evolving Planet Earth has continuously changed during its 4.6 � Core billion year existence as a result of interactions between its various subsystems � Mantle and cycles. � Crust. Why Earth is a Dynamic Why Earth is a Dynamic and Evolving Planet and Evolving Planet � The Core � The Mantle The mantle surrounds the core and The core consists of is divided into: � a small, solid inner region � a solid lower mantle � an asthenosphere that behaves � a larger, liquid, outer portion plastically and flows slowly Composed of iron and a small amount of nickel. � a solid upper mantle. Composed primarily of peridotite, an igneous rock made of olivine. 6