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Unit 2 Review and Solutions 1 • • • • Lithosphere (Rock) Hydrosphere (Water) Atmosphere (Air) Biosphere (Living things) – Volcano - L - Creates new rock, large amounts of ash produced, plate movements – A - larges amounts of ash enter the air polluting it, darkens the sky blocking the sun, sulfur dioxide – H - Gases like sulfur Dioxide mix with water vapour to create Sulfuric Acid (Acid Rain) – Bio - Ash can wipe out trees with pyroclastic flows, obviously kill people 2 • Precambrain (Eon) – Hadean (Era) – Archeaen (Era) – Proterozoic (Era) Largest aspect of the geologic Timeline Paleozioc Mesozoic (Triassic, Jurassic, Cretaceous) Cenozoic 3 • Geologic events take 1000’s of years to form • Human life span is 80 years • We cannot see formation and process happening • Human existance has really only been around for a fraction of time in the earths history (I step on a football field) 4 • Sedimentary - Rock that mainly forms in layers – Clastic (Cementation) – Biogenic (Formed form Living Organism and Sea Creatures when they die) – Chemical (Rock formed from natural chemical processes and cementation) • Igneous – Extrusive (Lava hardened on surface) – Intrusive (Magma hardened below the surface) • Metamorphic – Add heat and pressure to change the state of a rock from one form to another 5 • Relative Dating (Not an exact date) – Superposition - Each layer of rock is older than the one above it – Uniformitarianism - To understand how a geologic structure is formed we assume that present day processes operated in the same way thousands of years ago. (ex. Erosion) We can determine the relative age of a geological structure by observing how quickly or slow it is changing today – Fossil Correlation - A period of time can be define by it’s fossil content in a layers of rock 6 • Earthquakes happen because of the interactions at plate boundaries – Plates get stuck and move to create an earthquake 7 • BODY WAVES - Travel in the interior of the earth • P-Waves - Travel through any medium (solid or liquid) and reach the seismic station first • S-Waves - Travel through solid material only and are slower to reach the seismic station • SURFACE WAVES - Travel along the surface of the earth • Love Waves - Moves the ground from side to side • Rayleigh Waves - Travel slowly and make the ground move like the waves on a ocean or roller coaster 8 • Epicentre point on the earths surface directly overtop of the focus • Focus is where the movement takes place in the lithosphere 9 • Magma pushes through the centre of the ridge • As the magma/lava solidifies moves the existing rock outwards • Connected to the other ridges in the oceans • Convection currents in the asthenosphere help to contribute to motion that sets up plate movements • Plates are both oceanic and continental so when you’re pushing one your pushing the other 11 • Convection Currents - Take place in the upper mantle (asthenosphere) • They operate much like boiling water or pasta • Heats up to surface, cools off and falls back to bottom, where it then heats up and repeats the process • Think about laying a piece of toast on top! 12 • • • • • Location of Oceanic Ridges Sea floor Spreading Continental Shelves Seismological evidence (Quakes) Movement of crust caused the crust to crack forming plates • Magnetism 13 • Pacific Plate • Subducting under the surrounding continental plates • In theory the plate is getting smaller • N/A and Asia will collide (In theory) 14 • Divergent (Mid Atlantic Ridge) • Convergent (India and Eurasian Plate Himalayan Mountains) • Transform aka Strike Slip (San Andres fault) 12 • Mountain Building - Orogenic Process – Folding, Faulting, Volcanism – Folds upwards as the plates collide – Occurs when rocks pull apart and/or fracture – Volcanism molten rock reaches the surface forming volcanoes and new rock 13 • • • • Strike Slip Subduction Fault Extention Fault ******Collision Fault 15 • Stratovolcano aka composite cone • Layers of Rock and Ash • Branches of magma flows off the main conduit - Fissures - Harden to create even more pressure • When an explosion takes place they can reactivate old fissures and explode an entire side of a mountain causing great damage • Pyroclastic Flows are created as a result – Super heated ash debris moving downslope a a very quick speed 16 • Hot spots in the asthenosphere • Weaknesses in the crust 17 • Pyroclastic Flow - Landslide of Ash, rock and hot gases at 2000oF • They are unpredictable an often more deadly than an actual volcanic eruption 19 • Scientists can determine the age of rocks on both continents and in the ocean • Found continental rocks were older • Ocean floor and conveyor belt movements - New rock forms at the Mid Atlantic Ridge(200 Million years old, Pangaea Break up 20 • Review the Mid-Atlantic Ridge Profile and reading • Be aware of the continental margin features, Mid-Atlantic Ridge shape 21 • Tsunami’s are very destructive because they are not just one or two waves crashing ashore. • Rather, a Tsunami is a surge of water moving inland up to 2 - 3km • They destroy everything in their path and when they retreat they often carry many things out to sea • Formation…See pg 133 of text 22 • Tokyo lies on overtop the boundary of 3 major plates • Earthquakes happen regularly and they are a part of life there • Buildings are often built out of steel that can bend and contort as an earthquake shakes • Also the foundations of buildings are built on shocks to absorb the shaking • Lastly building are not built out of rigid concrete as they cannot withstand shaking 23 • Subduction is what causes Mega-Thrust Earthquakes • Stick slip properties (the bending of the continental landmass • Earthquakes releases pressure and snaps the continental plate back into regular position 24 • Volcanoes - Seismic stations to monitor earthquake activity around the volcano • Tsunamis - Early warning detection systems in the Pacific • Earthquakes - Seismographs to measure the strength of quakes and GPS to monitor the movement of tectonic plates • Mass media - Warnings over the internet, TV, Cell phones, Twitter etc. The word travels very quickly