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geography midterm 1 notes.docx

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Lakehead University

Energy, Matter and Systems Law of thermodynamics- energy does not disappear/consumed, just transformed and changes shape Universal law of attraction- what is “too much” seeks to go towards what is “too little” Energy transfer is shown in 3 types of systems: Open, Closed, Isolated. Open – can exchange both matter and energy within an outside system. Ex human body Closed – can exchange only energy within an outside system. Ex earth, diamond Isolated – doesn’t exchange either energy or matter within an outside system. Ex thermos Properties of a system: Components – system made up of diverse components that function as a whole Equilibrium state – state of the system that will not change unless there is a disturbance Stable Equilibrium – state system will return to if disturbed slightly Unstable Equilibrium – a small disturbance will carry the system away from one state to another Threshold Event – small changes that causes the system to shift from one state to another Disturbance – Perturbation – temporary disturbance, ex volcano may change climate but it will return Forcing – A more persistent disturbance, ex global warming Feedback loops – an interaction between components of a system, a change in 1 will affect 2 ect. Requires a disturbance to initiate change, ex warming causes arctic ice to melt, less ice means less solar radiation, therefore more warming 4 spheres within a closed system (EARTH). Geosphere Hydrosphere Atmosphere Biosphere Geosphere – solid earth and all related parts, changes everyday due to volcanoes and earthquakes - 3 basic parts: core (inner and outer), mantle (asthenosphere), crust (oceanic and continental) - contributor of particulate matter (volcanic ash) to atmosphere and atmospheric gas - gives salt to oceans (ions released from weathered rocks) - source of nutrients to all living things Hydrosphere – all the water on earth, an open system - moderates climate and transfers heat - water is essential in many of earths processes, from mineral formation to the erosion of rock - water cycle: how water moves along reservoirs (ocean, atmosphere, ground water etc) - temperature range of the earth allows water to exist is solid, liquid and gas Atmosphere – the body of gases that surround our planet. (79% nitrogen, 21% oxygen) - most dynamic system, weather is an example of this - from surface upwards: troposphere, stratosphere, mesosphere, thermosphere - contains the gas that all living things need to survive (oxygen, carbon dioxide) - ozone in stratosphere protects us from UV rays from sun Biosphere – all living things (plants, animals, organic matter) - an important sink for carbon and mediates the formation of minerals - photosynthesis maintains the oxygen content in the atmosphere - a recent addition to biosphere is human activity All 4 spheres are interconnected and have an influence on each other Gaia Hypothesis – James Lovelock, proposed that earths functions as a single super-organism that maintains conditions necessary for its survival, that the 4 systems are in delicate balance Reservoir – where energy or matter is stores in a system, rocks are carbons largest reservoir, ocean is waters reservoir, atmosphere is oxygen… energy can be transferred from one reservoir to another Flux – the rate of which these transfers take place. Plants absorb carbon from the atmosphere – the flux of carbon from the atmosphere to plants at a rate of 120 billion tones a year Residence time – the average time a substance is in a reservoir, it is calculated for steady state systems in which fluxes in (inflows) and out (outflows) of a reservoir are about the same and can be calculated: Sinks – large reservoirs with long residence time. Example rocks Lithosphere – ridged rocks of the crust and uppermost mantle Igneous rocks – rock formed from molten material Sedimentary rocks – rocks formed from sand, silt and clay Metamorphic rocks – formed under high pressure and temperature Basins – where sediment accumulates and layers over time, a thick sediment layer forms. Layers of calcium carbonate is limestone, sand is sandstone, clay is shale Trench – deepest part of the ocean Restless Earth – Plate Tectonics Without question, the theory of “plate tectonics” is the most important advancement in earth sciences in the 20 century. It provides the framework for earth processes (e.g., mountain building) that previously were known to exist, but it was unknown why these processes occurred. We now know what is inside the earth by earthquakes, volcanoes, and meteorites. The theory of Continental Drift: Alfred Wegener first proposed the theory of continental drift, which states that parts of the Earth's crust slowly drift atop a liquid core. Based on patterns of geology, fossils, and glacial deposits Wegener hypothesized that there was a gigantic supercontinent 250-200 million years ago, which he named Pangea, meaning "All-earth". Pangaea started to break up into two smaller supercontinents, called Laurasia and Gondwanaland, during the Jurassic period. By the end of the Cretaceous period, the continents were separating into land masses that look like our modern-day continents. Evidence of Continental Drift: - Geographic fit of South America and Africa - Fossils match across oceans - Rock types and structures match across oceans - Ancient glacial features three major scientific developments spurred the formulation of the plate-tectonics theory: (1) demonstration of the ruggedness and youth of the ocean floor; (2) emergence of the seafloor-spreading hypothesis and associated recycling of oceanic and (3) (3)precise documentation that the world's earthquake and volcanic activity is concentrated along oceanic trenches and submarine mountain ranges Plate tectonics – plates are driven by internal, mantel processes - gravity provides additional force to move plates Convection is like a boiling pot 3 basic types of plate boundaries: - Divergent – land moving apart - convergent – land overlapping, coming together - transform – land slides horizontally past each other As the Pacific Plate is consumed in subduction on all sidesthe Pacific Ocean will one day disappear Earthquakes along Convergent Zones with Subducting Oceanic Lithosphere Shallow earthquakes: The most destructive of these occur between the plates on the plate boundary. Shallow earthquakes also occur within the subducting plate and within the overriding plate near the plate boundary Intermediate and Deep earthquakes: The depth range defined as “intermediate” is 100 – 300 km deep while “deep” earthquakes are in the 300 – 700 km depth range. Intermediate and deep earthquakes occur only within the subducting oceanic lithosphere. Movements in the earths geosphere, called tectonic movements are responsible for the character, size and location of mountains around the world. They also form basins and divide continents -Most of the earth’s dynamic and changing character is directly or indirectly related to movements in the earth’s crust and mantle. -ridgid rocks of the crust and upper mantle combine to form the soilid lithosphere - the mantel below the lithosphere is not stable, which have clear influences on other parts of the atmosphere, geosphere and hydrosphere What causes plates to move? The earths upper mantle is hotter in some areas than others. This creates instability where hotter and less dense mantle moves upwards towards cooler and more dense mantle: hot mantle rises, cooler mantle lowers = plates moving Why don’t plates sink? Because it is buoyant and wont sink into mantel. Rifting – plate divergence that pulls apart the lithosphere. Rocks that fall between the cracks are called rift valleys The red sea, which separates east Africa and saduia Arabia, is an example of a narrow ocean basin this has formed at a divergent plate boundary. As the pieces drift apart, the rift zone widens and eepens to form a narrow basin. Magma upwelling from the mantle is reaching the sea floor and forming new oceanic crust. The climate in Antarctica is colder than the Arctic because the north pole lies in the middle of the ocean and the south pole is in the middle of a continent. Water is heater easier by the suns radiation) Biome – community that covers a large geographical area; boreal forest Physiography – description of earths landforms and other natural features on earth Subduction – pr
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