GLY1000 Lecture Study Guide TEST 1 Age of Earth 4 5 billion years Internal processes A process in the Earth system caused by Earth s internal heat ex Volcanism plate motion External processes A geomorphologic process ex down slope movement erosion that is the consequence of gravity or the interaction between the solid Earth and its fluid envelope air and water Energy for these processes comes from gravity and sunlight Theory A scientific idea supported by an abundance of evidence that has passed many tests and failed none A good hypothesis verifiability predictive power and reproduction How do we know Earth spins Foucault Pendulum As the Earth rotates the inertia of a pendulum keeps it in as close to the same plane as it can This is a consequence of Newton s Laws of Motion Geocentric view Earth is the center Helocentric view Sun is center Ptolemy Ptolemy s most important geographical innovation was to record longitudes and latitudes in degrees for roughly 8 000 locations on his world map making it possible to make an exact duplicate of his map Eratosthenes calculations Deduced that the Sun s rays at noon on this day must be exactly perpendicular to the Earth s surface at Syene and that if the Earth was spherical then the Sun s rays could not simultaneously be perpendicular to the Earth s surface at Alexandria Measured shadow then footsteps from Alexandria to Syene and calculated the Earths circumference Earths distance to the Moon 4 063 10 8 light years Earths distance to the Sun 0 00001581 light years Earths distance to nearest Star 4 3 light years Doppler Effect The phenomenon in which the frequency of wave energy appears to change when a moving source of wave energy passes an observer Doppler Shift Applies to light when objects are moving very fast We call this change red shift and blue shift Expanding universe theory States that the whole Universe must be expanding because galaxies in every direction seem to be moving away from us Age of the Universe 13 7 billion years measured current rate then back calculated Supporting evidence 1 Discovery of the expanding Universe 2 Modeling formation of elements 3 Star evolution Rate of expansion of universe Space itself is pulling apart at the seams expanding at a rate of 74 3 plus or minus 2 1 kilometers 46 2 plus or minus 1 3 miles per second per megaparsec a megaparsec is roughly 3 million light years Nebular Hypothesis Suggested that the origin of the solar system could be traced to a rotating cloud of gas and fine dust Immanuel Kant Where do elements come from and which were first in our universe Immediately after the Universe s formation big bang 14 bya it began to expand and cool The radiant energy produced quark antiquarks and electron positrons and other particle antiparticle pairs However as the particles and antiparticles collided in the high energy gas they would annihilate back into electromagnetic energy As the universe expanded the average energy of the radiation became smaller Hydrogen and Helium Galaxy formed 13 4 billion years ago from globular clusters spiral shaped cannibalizing neighboring galaxy now Solar system NOT DURING BIG BANG completed around 4 5 bya Heat source The flow of heat from Earth s interior to the surface is estimated at 47 terawatts and comes from two main sources in roughly equal amounts the radiogenic heat produced by the radioactive decay of isotopes in the mantle and crust and the primordial heat left over from the formation of the Earth Chemical composition of Earth Evolution of atmosphere s on Earth H He was lost to space because gravity can t hold lighter gases and undifferentiated Earth had no magnetic field Van allen belt Second from differentiation outgassing and impacts similar to modern volcanic gases Bulk composition of Earth elemental Mantle O Si Al Core Fe Ni Iron 34 6 Oxygen 29 5 Silicon 15 2 Magnesium 12 7 Other 8 Development of Earth s oceans timing source and evidence Water is a major component of volcanic gas Evidence for liquid oceans pillow basalts Bya deposits suggesting marine deposition First appearance of life 3 5 4 0 BYA Early life forms little evidence no hard parts teeth bones shells Earliest rocks with single celled eukaryotic organisms Current population of Earth and carrying capacity Scientists think Earth has a maximum carrying capacity of 9 10 billion people Current population 7 125 billion Earth s magnetic field geomagnetic field The magnetic field that extends from the Earth s interior to where it meets the solar wind a stream of charged particles emanating from the Sun Its magnitude at the Earth s surface ranges from 25 to 65 microtelsas Van Allen belts A radiation belt is a layer of energetic charged particles that is held in place around a magnetized planet such as the Earth by the planet s magnetic field The Earth has two such belts and sometimes others may be temporarily created Current atmospheric composition Nitrogen 78 and oxygen 21 with small concentrations of other trace gases Nearly all atmospheric water vapor or moisture is found in the troposphere so it is the layer where most of Earth s weather takes place Hypsometric curve A graph that plots surface elevation on the vertical axis and the percentage of the Earth s surface on the horizontal axis Alfred Wegener s continental drift hypothesis hypothesis proposed that the continents had once been joined and over time had drifted apart Evidence fit of continents fossil distribution location of gly formation glacial deposits Pangea Supercontinent that assembled at the end of the Paleozoic era Problems with continental drift Some scientists were opposed to his theory since neither Alfred nor anyone else had any proposed mechanism that actually caused the continents to move Stress force is applied Compressive squeeze Tensional pull stretch Shearing dif directions Strain the deformation resulting from stress Factors related to strain temperature confining pressure time type of stress Plastic behavior materials that can undergo extensive plastic deformation before rupture ex Paper clip Rigid behavior materials that rupture before any plastic deformation ex Glass EARTH has two physical layers 1 Lithosphere The strong rigid outer shell of the earth that encases the asthenosphere and contains the crust and the uppermost part of the mantle down to an average depth of about 100km and forms the rigid plates 2 Asthenosphere The weak layer of soft but solid rock comprising the lower part of the upper mantle and
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