Geo 101N 4th EditionExam # 1 Study Guide Lectures: 1 - 9Lecture 1 (1/28) What is geology? What is the evidence discussed in class for expansion of the universe? What are the most abundant elements of the Earth as a whole, and of the crust?Geology: The use of scientific methods to study the physical processes that shape our planet.Why Earth is Special- Earth has a quartz rich crust- Hot interior; evidence of active tectonics- evolving landscapes-volcanic activity/creation of new land mass- Earth orbits in the “just right” zone in the solar system enough radiation from the sun; not too muchWavelengths of light- The color of light from stars isstretched (shifted) towardwavelengths @ the red end of thespectrum (red = longer wavelengths)- Color from a moving object willappear to be a different color - An object moving away will have longer wavelengths (red); comingtowards = shorter wavelengths (blue/purple)Edwin Hubble/Universe expansion- Created the classification for galaxies still used today; Hubble Sequence- discovered a constant relationship between a galaxies' “redshift” and distance, which helped to eventually prove that the universe is expanding- proved that other galaxies exist outside of our own (Milky Way)When was the universe born?- Approx. 13.8 Ga (billions of years ago)Lecture 2 (1/30)Raw Materials & Formation of the Solar SystemHow did the chemical elements form? Which formed in the “big bang”, which in stellar fusion,and which in supernovae?Building Blocks:- atom: smallest particle that retains the characteristic id an element- protons (+ charge; found in nucleus), neutrons (neutral; found in nucleus) and electrons (- charge; charged cloud around the nucleus) - atomic number: the # of protons in the nucleus. The atomic number is the definition of the atom, anything with 6 protons is Carbon etc.Element Formation: - At the moment of the big bang there was no matter, the first instant after matter was formed; protons, neutrons and electrons formed (w/in 3 minute Hydrogen and Helium formed)- Started a rapid cascade of event; the new born universe expanded, cooled and became less denseAfter the Big Bang- The expansion & cooling of the universe allowed atoms to begin bonding- H forms and begins fueling stars- Atoms & molecules group together in nebulae due to gravity- Gravity caused nebulae to collapse, increase in temperatures, density and rate of rotation- Condensed nebulae formed flattened accretion discs- Heat and mass from collapse “ignites” nuclear fusion (combination of 2+ atoms to form heavier atoms)Elements Form in the Stars- Mass of a star dictates the elements produced (ie, smaller mass stars such as our sun “burn” slowly, live longer and create lighter elements ie carbon)- Stellar nucleosynthesis:o When a star runs out of fuel they heat due to an inward collapse/implosiono Becomes a cataclysmic explosion (supernova: this is when/how heavier elementsare formed)- Big bang nucleosynthesis formed lighter elements (H, He, Li, Be and B)- Heavier elements born of stars (atomic #’s 6-26)- Supernova create elements heavier than 26, that is, with atomic numbers higher than 26The Modern Solar System: Where are we?- Earth is 1 of 8 planets orbiting our sun, 3rd in line from the sun- Our solar system is located on an arm of the galaxy called the Milky Way- Consists of 300 billion sunsSolar System Formation- Nebular Theory: nebulae formed ~4.56 Ga (billion years ago)o Nebula: a cloud of gas containing H & Heo Heavier elements produced from stellar nucleosynthesis present- These materials collect into a disc shape with a ball formed at the center (called a protoplanetary disc)- The ball at the center grows hot & dense- A fusion reaction begins giving birth to a sun- Dust rings condense into particles; particles form planetesimals (beginning of a planet)- Planetesimals start colliding (evidence can be seen on Mercury and the Moon in the form of craters), this is planetary accretionAccretion of Earth- Not entirely ceased yet today but it is much slowed- The meteor that is thought to have caused the end of the dinosaurs was accretion- Small meteors and dust particles continue to add ~100,000 kg to earth each day (relativelya negligible amount) Nature of Our Solar System- Our sun = medium sized star orbited by 8 planets; diameter is 109 times larger than the diameter of Earth)- 99.85% of the mass of our solar system is in the sun- Planet: set of criteria established by the IAU (International Astronomical Union)- Is a large solid body orbiting a star - Has nearly spherical shape- Has cleared it’s neighborhood of other objects - Pluto cannot meet the 3rd criteria and so became the founding member of the order of dwarf planets Planets- Terrestrial: Mercury, Mars, Earth and Venus- Small, dense, composed of rock- Have compositional layers (crust, mantle, core)- Relatively thin atmosphere- Jovian (Jupiter-like/Giant): Jupiter, Saturn, Uranus and Neptune- Large, gas giants- Much of the volume is a thick atmosphere overlaying oceans of liquid gases- Characterized by many moons or ring systems- Variation in composition:- Proximity to the forming sun was a key factor in what formed where in the early solar system- Denser matter (metals, minerals) condensed close in while carbonaceous matter and various ices condensed farther outLecture 3 (2/02) How did the Earth, moon form? When did each form? What is the evidence? Why did the earthdifferentiate into layers? What are these layers called and what makes them unique from each other? Planets- As they grew they began to heat up- The hotter they became the more spherical they became- Planet composition varies because of what materials were available when and where they formedDifferentiation-Differentiation: the settling of layers -began when the earth was still a molten ball-heavier materials (those more dense) settle “down” or “in”, for earth that is primarily metallic iron (Fe) and Fe seeking elements-silicates stayed at the surface making up the crustMoon Formation-~4.53Ga a Mars sized protoplanet (“impactor”) smacked into young earth-The planet and part of the mantle were disintegrated; this started the earth spinning and launched materials around the earth, the moon was born of these materials-Earth was completely molten again after impact-The earth absorbed Fe from the impactor-Within a day of impact gravity had reshaped the earth into a sphereThe Earths Layers-Crust-Continental: granite, average