Term
1. Features of the ocean floor
– Mid-ocean ridges and rises: underwater mountain ranges
*Ridges tend to be steeper and the width narrower
*Rises are opposite with no central valley.
- trenches: deep gashes in the ocean crust
- convection currents in the mantle causes seafloor to spread at ridges and rises
*new crust made at ridges/rises
- oceanic crust sinks into trenches
*subduction zones have oldest ocean crust |
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the earth is divided into lithospheric plates that separate, collide, or move parallel to one another
*creates certain ocean and land features |
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| locations of earth quakes |
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| convection currents in the mantle |
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– Paleomagnetism: Rock evidence showing the past movement of earth’s magnetic poles, found mainly in oceanic rock.
– Earth’s magnetic poles flip and change locations.
– Normal and Reverse Polarity
• Occurs every few million years
• probably due to turnover of liquid in the outer core
– Fe and other magnetic elements in lava solidify w/ the magnetic poles
– Fe sediments align w/ poles when setting out of water
– Magnetic reversals are recorded on ocean floor at ridges and rises
– Magnetic signatures match each other on opposite sides of ridges |
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Types of convergent boundries
• 3 types of convergent boundaries: Cont-Ocean, Ocean-Ocean, Cont-Cont.
• Cont-Ocean: volcanic arcs, trenches, subduction zones, shallow to deep-focus earthquakes
• subduction zone: overriding plate scrapes off seafloor sediments and island arcs
• subducting plate is heavier and denser
• Ocean-Ocean: island arcs, trenches, subduction zones, deep-focus earthquakes
• Cont-Cont: mountain ranges, slide underneath but can not sink, not many volcanoes |
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Types of divergent boundries
• Divergent or Rift Zones: separating plates, new crust
• 2 types: Cont-Cont, Ocean-Ocean
– Cont-Cont: rift valleys, geysers, hot springs, long lakes, volcanos, shallow earthquakes, lava flows, pillow lava in lakes, hydrothermal vents, convection cell underneath
– Ocean-Ocean: ridge or rise, same as above with pillow lava and hydrothermal vents |
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Transform boundries
• Transform: plates slide past or next to each other, on land or water.
– shallow earthquakes, escarpments (continuous line of slopes or cliffs), crust not destroyed or created. |
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Active margin
• Active Margins: edge of a continental that is tectonically active
– usually a trench is offshore and volcanic range near coast |
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Hot spots
• Found in center of plates and along ridges/rises,
• Magmatic plume from mantle, not a convection current
• Plates move over the stationary hot spot
• Creates island chain where islands move off hot spot
• Chain of extinct volcanic islands off hot spot
• Only active island is on hot spot
• Lifespan of hot spot is 100 million years.
• On land: geysers, hot springs, volcanoes, small concentrated area compared to rift zone. |
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• Since 1900:
– Edwin Hubble’s (1889-1953) 2 big discoveries:
• Discovered the Andromeda galaxy approximately 2.5 million light years away
• Galaxies are moving rapidly away from each other
– not in random directions |
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Evidence for Big Bang
• Oldest object is a gamma-ray burst 13 billion light-years away.
– Brightest, most intense radiation event in the universe.
– Occurs when massive star collapses into a black hole.
• Calculations show that expanding universe derived at a single point
• Immense amount of space in an atom.
– conceivable atom reduced to an extremely small amount of space
• The Big Bang should produce an immense amount of heat.
– Cosmic background radiation of 2.75 degrees above absolute zero (lowest temperature possible).
• The abundance of H and He (98% of universe) shows the formation from an explosive event
– more complex elements formed through atomic fusion in stars from H and He. |
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Distances and definitions
• Light-year: distance of light traveled in one year - 186,000 miles/sec |
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Distances and definitions
• Universe - the totality of space, time, matter, and energy. |
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Distances and definitions
• Superclusters/localclusters - clusters of galaxies that are usually gravitationally bound |
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Distances and definitions
• Galaxy - A collection of stars that bound together by gravity. |
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Distances and definitions
• Solar system - planets that orbit a sun or group of suns. |
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Distances and definitions
• Star - a glowing ball of gas held together by its own gravity and powered by nuclear fusion. |
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Distances and definitions
• Planet - a space body within the solar system:
• is in orbit around the Sun
• has sufficient mass to produce a round shape
• cleared the neighborhood around its orbit
• not a satellite (a moon) |
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Distances and definitions
• Moon - a small body that is in orbit about a planet. |
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• Spiral galaxy - flattened disc of stars rotating around the center of a black hole.
• Galactic bulge - the center of a spiral galaxy, spherical in shape, stars closer together
• Galactic disk - the sheet of young stars, dust, and gas revolving around the galactic bulge.
• Galactic halo - ancient stars and dust outside of the galactic disk. |
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• Nebular Theory
• A previous star was present and exploded (supernova) producing vast amounts of gas and dust.
• Dust and gases collect together forming larger bodies.
• Passing of a nearby star creates rotation in solar system.
• Most dust/gas begin to contract by gravity into protosun.
• Smaller eddies of gas/dust begin to contract into protoplanets
• Protosun has 99.9% of material, great heat from fusion produces light.
• Explosion of solar winds (ions from the sun) blow lighter gases far forming outer planets
• Heavier gases and dust remain closer forming inner planets. |
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• Inner Planets
• Rocky crust, mantle, iron/nickel core
• No or few moons
• Small or no atmosphere
• Small diameters
• Have or had some degree of plate tectonics |
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• Outer Planets
– Small core of rock or liquid
– Liquid hydrogen mantles
– Thick atmosphere of H and He
– Large diameters
– Many moons/all have rings |
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• Asteroid Belt between Mars and Jupiter
– Asteroids - made of carbon, or rocky material, or iron.
– Sizes: 10 meters to 1000 kilometers in diameter
– 400,000 orbit Sun |
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• Kuiper Belt – a flat disc of comets and dwarf planets beyond Neptune, rotates around the sun.
– Comet: a space body made of ice, dust, and rocky material that orbits the Sun. |
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• Oort Cloud – a sphere of comets extending 1 light year away from the Sun.
– Contains billions of long-period comets
– Comets in the Oort Cloud revolve in random directions around the Sun. |
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Devonian period
• Devonian, 408-360 Ma, Nov 28-Dec 3
• Acadian and Ural Orogenies
• Age of Fishes
• Transition of vertebrates to land
• First trees and seed-bearing plants |
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Devonian period
• Climate is really controlled on a local level, especially on Laurasia.
• Most of continent lay in the rain shadow behind the mountain ranges
• Erg
• Rain was falling on the eastern side of mountains around Laurasia.
• Forests growing on eastern side |
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Devonian period
• Ostracoderms ("shell-skinned") - jawless fishes completely covered in armor of bony plates.
• The Placodermi (bony-head fish) – fish with armored head and thorax, rest of body was scaled or skin.
• Dunkleosteus:
• 30 ft long, placiderm, top predator in ocean |
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Devonian period
• Crossopterygians: group of lobe-fin fish with muscular fins for moving occasionally on land
• Ichthyostega: one of the first true amphibians to exist on land |
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Devonian period
• Development of woody plants; the ability to grow taller to reach open sunlight and to carry a greater weight of branches and leaves.
• 4 Plant Guilds:
• Trees
• Shrubs
• Weeds
• Survivalists
• Archaeopteris: earliest modern tree, grew 30 meters tall |
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• For North America, Carboniferous divided into 2 periods:
• Mississipian (360-320 Ma) known for its limestone deposits across Laurasia
• Pennsylavanian (320-286 Ma) known for swamplands and coal deposits when regression occurred later. |
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• Late Carboniferous, Gondwanaland collides with Laurasia to form Pangea.
• Collision of Gondwanaland begins the last phase of Appalachian Mountains – Appalachian orogeny. |
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• Vigorous growth of trees may have sucked much of the CO2 out of the atmosphere, producing a surplus of oxygen.
• Oxygen levels were higher during this time than at any other time in the history of the Earth (30% of atmosphere).
• Gondwanaland has its own very distinct flora, dominated by glossopteris |
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| Stocky-bodied and armoured millipede-like Arthropleura was 1.8 meters long |
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Carboniferous period
– The first reptiles appear |
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Carboniferous period
– The key feature in the origin of reptiles is the amniotic egg.
– Durable outer shell protects embryo from drying
– Egg can be laid on land
– Yolky part of egg provides nutrition; sac contains embryo and another sac collects waste products.
– Young adult hatches; no need for larval stage
– Eliminated need to lay eggs in water, allowing vertebrates to live and reproduce on dry land for the first time. |
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Carboniferous period
– General trends how E’s food chain is built.
– Plants first on land:
– Reproduced by spores but tied to water
– Seed allows plants to grow on dry land
– Seeds are opportunistic waiting for water to germinate.
– Animals follow plants:
– Insects eat plants and are in turn food for other animals
– Lobe-finned fishes and amphibians still tied to water for reproduction.
– Vertebrates eat plants, insects, and other vertebrates
– Amniotic egg allows reptiles to colonize dry land. |
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– Early in Permian, Pelycosaurs (fin backed reptile) became the top carnivores and herbivores.
– Dimetrodon and Edaphosaurus
– attained lengths ~ 3 meters
– The large dorsal "sails" may have helped control body heat
– advantage over more sluggish sail-less relatives
– Limited to the equatorial tropics. |
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– Therapsids (Mammal-like reptiles)
– Skulls resembles mammals
– Legs positioned more vertically under body
– Teeth were dog-like
– May have been endothermic (warm-blooded) and hair
– Cold-adapted. |
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– Permian flora changes from swamp conditions to dry
– Biggest change is the growth of gymnosperms (flowerless seed plants); conifers dominate |
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– Evidence for extinction:
– 1st: Fossilized pollen shows biological complexity up until the Permian; then worldwide fungal material at Triassic
– Whatever died on land, fungi being decomposers took over most of plant life on land
– 2nd: Several C-12 spikes in rocks at this time
– all life is made of C-12 and maintains a steady rate unless an extinction occurs; more C-12 seen in rocks at Permian extinction.
– 3rd: Huge amounts of lava flowed out of Siberia for a million years
– Huge emissions of Cl2, SO2, and CO2.
– 4th: Layer of black shale deposited in ocean
– Represents anoxic conditions where organic material is not decomposed
– not enough O2.
– 5th: Ocean regression at end of Permian
– Triassic rocks are stained red color; means a lot of oxygen taken out of atmosphere to form rusted minerals.
– Many of these rocks exposed from regression
– 6th: Huge rise in worldwide temperatures (up to 6°C)
– 7th: Meandering rivers
– Lots of sediment from continental eroding
– Little plant life |
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– Crinoids (echinoderm): animals that have stalk, long arms, head with mouth.
– Most crinoids lived attached to the sea-floor by a flexible stem
– Crinoids have a cup-shaped head with long, branching arms.
– Remains can form thick LS. |
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– Blastoids (echinoderm), a long stalk with a head at the top.
Fragile and slender arms attach near the mouth of the individual |
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