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Lecture 2

GSC 102 Lecture 2: GSC Exam 2 Study Guide

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University of Miami
Geological Sciences
GSC 102
Leech Peter

GSC Exam 2 Notes 9/26/2016 8:58:00 PM 12. The Age of the Universe • Cepheid stars pulse with a frequency which is proportional to their luminosity • 1 light year = 5.9 trillion miles • Sun is 8 lightminutes away • We use parallax to determine the distance to (relatively) nearby objects • There are plenty of fuzzy, gassy, diffuse nebulae in the galaxy • Andromeda Galaxy is about the most distant thing you can see with the naked eye • DOPPLER EFFECT is when a wave emitted or received by a moving object appears to change • Noises from things moving towards us get higher in pitch, and from things moving away from us get lower • Light from things moving towards us gets bluer, and from things moving away from us gets redder • all very distant galaxies are REDSHIFTED • HUBBLE’S LAW observes that more distant galaxies are moving away from us more quickly • Hubble’s Law implies that space is expanding • Anything with a temperature emits blackbody radiation • As something gets hotter, it emits wavelengths (or colors) of higher energy • cosmic microwave background is essentially the temperature of the Universe • Over time, gravity should be causing the expansion of the universe to slow down • However, the expansion actually appears to be ACCELERATING. This acceleration is explained by DARK ENERGY 13. Atoms and the Milky Way • As the Universe expands and cools, they combine to form the simplest atoms, hydrogen and helium • Variations in the Cosmic Background Microwave show that the early Universe was slightly lumpy. These lumps are areas of slightly more dense gas which would eventually begin to collapse under the influence of gravity. • Small isotopes can undergo FUSION, although it requires huge temperatures and pressures • Hydrogen atoms have one proton • Helium atoms have two protons • This is how our Sun works, by fusing hydrogen into helium • Fusing higher elements requires higher temperatures and pressures • Iron-56 is more abundant than similar elements because it is the most stable element • Elements heavier than iron are mostly formed by two other processes: the s-process and the r-process • The r-process is element formation in SUPERNOVAS • We can measure the masses of galaxies by using gravitational lensing • Gravitational lensing suggests that galaxies are heavier than they look • According to Keplerian dynamics, bodies orbiting a large mass should move faster when they are closer to it. But galaxies don’t rotate like that. The distant stuff orbits at the same speed as the near stuff • This implies that galaxies are embedded in a disk or halo of matter that we cannot does not interact with light • Calculations suggest that around 85% of all mass in the Universe is dark matter 14. Formation of the Earth • Cambrian Period = when life started on Earth • Chronometrically = not an exact date, an estimation • Stratigraphically = more exact and accurate dates • Precambrian is 87% of Earth’s history The Hadean: the formation of the Earth and Moon • Early part of Earth is thought of as having volcanoes, poisonous gases, fire, etc. (Hell) • 4.6 billion years ago, Solar System forms a huge rotating cloud of dust and gas by accretion (turns into planets & other stuff) • As the big cloud of stuff clumps up and gets smaller, it spins faster • HL Tauri’s protoplanetary disk – an example of angular momentum • Homogeneous Accretion – a mixed mass of metals and stony materials that creates a planet (Earth) o Eventually the planet melts and the materials separate o Molten stone and molten metal does not mix together (oil and water); this is why the Earth has a metal core and a stony crust and mantle • Earth’s “first atmosphere” is probably made of hydrogen and helium and escapes to space quickly because these gases are very light • The inner planets are close to the sun, so the gases are stripped o “Frost line” – planets beyond this line are farther from the Sun and hold on the gases (“Gas giants”) • Planets close to the sun (terrestrial planets) are made up of the same materials (kinda) – metal core & rocky mantle • The gas giants are made up of mostly gases and ice • If the moon had co-accreted with the earth, it would have the same composition as the Earth • If the earth had captured the moon, it would have a very different composition from the Earth o The Earth & Moon have very similar compositions, except for the Iron part (Earth’s core) • We think the moon formed when another planet smashed into the Earth and blasted a part of the mantle back into space o Bc of this, the Moon’s composition is exactly like the Earth’s mantle • When the moon is molten, granite floats to top and basalt sinks to bottom (surface of the Moon, as a result, is a granite-like material) • Between 3-3.5 billion years ago, volcanic eruptions released darker basalt-like material onto the Moon’s surface • Lunar MARES like the Sea of Tranquility are made of roughly the same stuff as oceanic crust on Earth • Rocks collected during Apollo missions suggested LUNAR CATACLYSM o LUNAR CATACLYSM – o Rocks are not older than 4 billion years ago o LATE HEAVY BOMBARDMENT – asteroid storm on the Moon o NICE MODEL suggest that Jupiter moves outward through an asteroid field and moves asteroids into the Solar System and towards the Moon • The tides as a brake on the Earth’s rotation, but also speeds up the orbit of the Moon o Overtime, Earth’s rotation is slowing down and the Moon is speeding up o The Moon must move away to compensate (1 inch per year) o In the past, days were shorter and the moon was closer (when the earth first formed, the days was 6 hours long and there were 1400 days in a year) o The Moon is tidally locked to the Earth, you always see the same side of the Moon • The oldest exposed rocks on earth are in Canada at the Acasta Gneiss o A metamorphized version of granite, plate tectonics must have been operating in the early Archaean (4 billion years ago) • Zircons in Australian Hills are dated 4.4 billion years old, some sort of igneous rock must have existed before the Late Heavy Bombardment • Chemistry suggests they were formed in liquid water • Pillow Basalt are distinctive rocks that only form in water, meaning that finding the oldest of these tells us when liquid water formed on earth o 3.7-3.8 billion year old pillow basalts = when water was formed o Evidence for water 400 miles under Earth’s surface • Volcanoes are the major source of water on Earth – heated and melted ringwoodite which released chemically bound water onto Earth • Some of Earth’s water may have come from comets and asteroids • Besides water, volcanic activity released nitrogen and carbon dioxide to create Earth’s second atmosphere o Although there was a lack of oxygen, other living creatures can survive anyway (not humans) 15. The Origin of Life • Four essential components of life o Proteins: chains of amino acids; proteins are used to build living materials, and as catalysts in chemical reactions in organisms (enzymes) o Nucleic acids: large complex molecules in cell nucleus ▪ DNA ▪ RNA o Organic phosphorus compounds: used to transform light or chemical fuel into energy required for cell activities o Cell membrane: to enclose the components within the cell • Stanley Miller (1930-2007) conducted the now famous MILLER-UREY experiments to discover if organic chemicals could arise naturally under early Archaean conditions o He combined methane, ammonia, water, and hydrogen, and added energy via an electric spark o Eventually produced the simple amino acids glycine and alanine • Amino acids have been found in meteorites recovered on Earth • Material collected from comet WILD 2 by NASA’s STARDUST mission contained amino acids • The amino acids which are easiest for Miller-type experiments to produce appear to be those which are coded for in most ancient DNA • When amino acids are heated together with phosphoric acid, they form proteinoids o Proteinoids have been found naturally occurring near volcanic vents in Hawaii and are a leading candidate for the early cell wall • Like proteins, the nucleic acids RNA and DNA are just long polymers of simple molecules • Certain types of clay have a regular surface which helps to arrange RNA bases – they also catalyze their polymerization • ATP is the molecular currency of energy; all organisms use ATP to move and store energy • DNA MAKES RNA WHICH MAKES PROTEINS • Before photosynthesis and before the ozone, how did life appear? o Hydrothermal vents provide energy and all kinds of chemicals and minerals; shielded from the Sun’s rays ▪ Today, home to thriving communities all without the benefit of sunlight • RNA, DNA, proteins, and ATP together = prokaryotic life (bacteria and archaea) • Prokaryotes reproduce asexually by simple cell division, which restricts genetic variability • Little evolutionary change for more than 2 billion years • Bacteria and archaea are prokaryotes • Eucarya are eukaryotes • Eukaryotic cells are larger, reproduce sexually, and have a nuclear membrane and organelles • All eukaryotes have mitochondria • All photosynthetic eukaryotes have mitochondria and chloroplasts • Mitochondria and chloroplasts cannot be created but must be inherited • Mitochondrial DNA is different from nuclear DNA • Lynne Margulis argued that mitochondria and chloroplasts had begun as ENDOSYMBIOTIC BACTERIA o Symbiosis is when 2 organisms live together for mutual benefit • All life originates from a common ancestor o Horizontal Gene Transfer means that not all of our genes come from one ancestor o Universal common ancestor wasn’t the first/only thing alive • Living things prefer carbon-12 from the atmosphere, so biological carbon is isotopically light o Fossil carbon will have a distinct isotopic signature • Stromatolites form when Cyanobacteria or other microbes form mats which trap sediment o Found fossils that appear to be stromatolites 3.7 billion years ago or microbial sediment structures • Banded Iron Formations represent the first evidence of photosynthesis, around 3-2.5 billion years ago • Free oxygen (O2) is extremely unstable, only exists in atmosphere because photosynthetic organisms produce it • The first oxygen photosynthesizers are cyanobacteria, which are prokaryotic and appeared about 3 billion years ago and were well- established by 2 billion years ago • The oxygenation of the Earth’s atmosphere marks the beginning of the PROTEROZOIC and the formation of Earth’s third atmosphere 16. The Proterozoic • Laurentia forms around 1.8 billion years ago o Continental crust that has remained relatively stable for the past 600 million years o Becomes North America • 1.6-1 billion years ago – grenville orogeny is some of the first evidence for a supercontinent RODINIA • John Tuzo Wilson (Canadian) hypothesized the Wilson Cycle that the Atlantic ocean basin opened and closed roughly every 500 million years • At the beginning of the Proterozoic, the Sun was 80% as bright as it is today (getting hotter over time) o However, the Earth’s temperature has stayed roughly the same (The Faint Young Sun Paradox) Initial change  Warmer climate  increased temperature, precipitation, vegetation  increased chemical weathering  increased co2 removal by weathering  reduction of initial warming • Tillite is formed in the presence of ice – sedimentary ice made of big, medium, and small rocks • Glacial striations are also formed by ice • By looking at magnetic directions of the rocks/crystals, we can figure out where the rocks were formed • At one point, the entire planet was covered in ice • Mikhail Budyko (Russian) built a simple climate computer model to simulate ice ages o In the ICE ALBEDO (shininess) EFFECT causes RUNAWAY GLACIATION – ice on the Earth makes the sun reflect off of it, and makes the Earth colder • Stromatolites – 3.5 billion years ago • Acritarchs – 2.1-2.6 billion years ago; first eukaryotes • Metazoans – 630 million years ago; first multi-cellular animal o Possibility 1: symbiosis between diff species of bugs ▪ Problem: if this happened, your different cells would have different DNA o Possibility 2: failure of reproducing unicellular organisms to properly separate ▪ Problem: we never see this occur naturally o LEADING HYPOTHESIS: multicellular animals evolved from a unicellular Flagellated Eukaryote which formed colonies • 630 Million years ago: the Ediacaran Fauna o cannot be assigned to a phylum o Dickinsonia species o Almost-symmetry o Lack digestive system o Possibly digested microbial mats on the floor of the ocean and absorbed the nutrients through their skin o Fossilization suggest that some have hard-ish parts made of keratin or chitin • Fossils of the SMALL SHELLY FAUNA appear in the last part of the Ediacaran o Start making mineralized hard parts, but not the kinds that humans are made of Why evolve mineralized hard parts? • Protection • Action • Cloudina – one of the best known members of the SSF (6-15 cm) • Halkieria - “a slug in chain mail” 17. The Cambrian (541-485 million years ago) • Last 540 Ma: Phanerozoic Eon “Evident life” o 3. Cenozoic “Recent life” o 2. Mesozoic “Middle life” o 1. Paleozoic “Old life” • *Paleozoic* o Paleo - Permian o Cut - Carboniferous o Don’t - Devonian o Silly - Silurian o On - Ordovician o Come – Cambrian • During Cambrian, Gondwana was moving North and so was Laurentia (Wilson Cycle) • Cambrian was characterized by large, warm, shallow seas • Cambrian starts with a trace fossil called Treptichnus burrows o First occurrence at Fortune Head in Newfoundland • Simple sponges are built of unspecialized cells which can change function o Simplest multicellular life o No nervous, circulatory, or digestive system o Lack organs and real tissue • Earliest sponges are Archaeocyathids o Form a calcite skeleton o Built first ever reefs during the early Cambrian • Burgess shale – celebrated for its preservation of soft party parts from the Cambrian • Genus Opabinia o Hypothesized to be an early arthropod o 5 mushroom shaped eyes o Weird proboscis o No jointed appendages o Mouth points backwards • Genus Hallucigenia o 1977 - Early relative of modern velvet worms (an extant invertebrate phylum) o 1991 – Original interpretation was upside down o 2015 – Head position figured out • Genus Pikaia o Early chordates • Genus Anomalocaris o “Unusual shrimp” 1982 o Genus Peytoia ▪ Type of jellyfish o Huge predator (3 ft long) o Top of Cambrian food chain • Arthropods split into 4 main groups depending on number and arrangement of head appendages • The Burgess Shale contains arthropods that don’t fit in the groups • Prompts the argument that the Cambrian was a time of greater experimentation than later • As you evolve through time, species split into smaller groups and the ecosystem becomes more diverse (Cone of increasing diversity) o Gould argued against cone of increasing diversity and suggested that members of the Burgess Shale fauna supported the decimation and diversification model • Trilobites – shelled organism during the Cambrian o 17,000 described species o single most diverse class of extinct organisms o Early Cambrian – Permian o Make multi-lensed eyes made of calcite-like material • Marine species with mineralized hard parts are also molted which leaves even more fossils • CAMBRIAN EXPLOSION – relatively sudden appearance of a large, diverse ecosystem in the Cambrian o When real animals show up very quickly • Precambrian animals are rare and not obviously animals • Cambrian animals are abundant, fossilize easily, and are obviously animal • Cambrian substrate revolution – evolution of burrowing organisms o Substrate becomes softer and soupier o Appearance of burrowing animals could have stopped soft bodied Ediacarans from fossilizing • Mass extinction that is associated with the end of the Proterozoic • Gradualism is the idea that evolution is slowly happening all the time • Punctuated equilibrium: organisms and ecosystems evolve to become successful in their environment, and then remain unchanged until the environment changes (Organisms only change if the environment/ecosystem does first) • Species or ecosystems remain stable for long periods, when speciation or evolution occurs it is relatively rapid 18-19. The Ordovician and Silurian • Adam Sedgwick thought Welsh rocks were Cambrian, while Roderick Murchison thought they were Silurian  Both disproven by Charles Lapworth who said they are Ordovician • The Iapetus Ocean begins to close o Baltica and Avalonia are beginning to crash into Lauretia o Gondwana moves over the South Pole • Mountains erode, creating sedimentary rocks west of the mountains • Sea level remains relatively high • Base of Ordovician is defined by a specidic species of CONODONT - teeth o Conodonts and graptolites mark almost every single geological period during the Paleozoic o Graptolites were reconstructed as large, floating colonies of tiny animals o Condont teeth represent the first appearance of hard hydroxyapatite body parts – first of humans’ ancestors to have hard parts • Great Ordovician Biodiversification Event (3x as diverse) o GOBE “filled out” those phyla with modern classes and orders o Species of Cambrian explosion lived in largely warm and shallow seas o The species of GOBE will begin to expand into the open ocean • The Paleozoic fauna is also called the “Brachiopod-rich assemblage” o Rare o Clam-like • Diploblasts (2-layers of cells) and triploblasts (3 layers of cells) have differentiated cells o The third, middle later in triploblasts forms organs o Diploblasts cannot form true organs (jellyfish, phylum cnidaria) ▪ Medusa – like jellyfish ▪ Polvo – like anemones • Corals are also Cnidarians o Earliest corals are the TABULATE corals – form tubes with horizontal septa, no vertical divisions o Later corals are the TETRACORALS and HEXACORALS o Changes in coral type are possibly driven by changes in ocean chemistry o Calcite skeletons probably evolved several times from soft-bodied
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