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Earth Cycles Kim Bergwerff Biogeochemical Cycles “The matter that forms the outer layers of our planet….rocks, water, and atmosphere….are forever being shifted from place to place.” Overview • The Earth operates in cycles. • There are three main Earth Cycles : The Rock Cycle, The Water Cycle, and The Atmospheric Cycle. • Earth’s Cycles are connected and each influences the others. • Scientists are using information from the Earth Cycles to try to determine what our future climate will be like. The Rock Cycle • Geologists classify rocks into three groups. Igneous Sedimentary Metamorphic • Form when molten rock cools and becomes solid. • Are categorized both by the way they form and their mineral content. • All rocks begin as Igneous Rocks. Two Categories of Igneous Rocks Based on Mode of Formation • Result of magma that reaches the surface, becomes lava, and cools rapidly. • Cools down within a few hours. • Also known as Volcanic rock. • Individual crystals are too small to be seen by the naked eye. • Form deep within the Earth’s crust at very high temperatures. • May take thousands of years to cool down. • Individual crystals are larger and can be seen with the naked eye. • Also known as Plutonic rock. • Eventually the rock makes its way to the surface. Two Categories of Igneous Rocks Based on Mineral Content • • • • Also known as acidic. Rich in quartz. Light colored. Example - Rhyolite • Also known as basic. • Rich in iron and magnesium. • Darker colored. • Example Basalt * All Rocks Begin as _____ ____ ! • Form from the sediments of igneous rocks. • Result of weathering and erosion on igneous rocks. • Many types, three are very common: Sandstone, Shale, and Limestone. • Made from sand grains and igneous rock sediments. • Result of sediment that is buried by beach sand deep underground. • Pressure and heat from the earth’s interior and minerals from the water form a “cement” to hold the grains together. • Made from silt and clay combined with igneous rock sediments. • Most abundant sedimentary rock-70% of the sedimentary rocks are shale. • Usually found among layers of sandstone or limestone. • Made from compacted decomposed plants and animals and igneous rock sediments. • Also arise from skeletons of microscopic organisms. • Calcium carbonate from decomposed plants, animals, and microscopic organisms makes up the majority of the composition of limestone. *Igneous rocks weather and erode and combine with other material to form ________ _____ ! • Form when extreme heat and pressure is applied to igneous or sedimentary rocks deep within the Earth. • The heat and pressure cause chemical changes making the resulting rock very different from the original rock. • Final rock depends on: amount of pressure, heat, and time. Three Common Metamorphic Rocks… • Limestone Marble - grains re-crystallize to form Marble • Shale Slate - minerals are rearranged due to heat and pressure • Coal Diamond - 75 to 120 miles below the surface from the melting of coal and other rocks, must be mined * When extreme heat and pressure change the composition of a rock it becomes a ________ _____! And…… * When metamorphic rocks return to the mantle and join magma they form _______ _____ once again! And the Cycle Continues… Moh’s Hardness Scale • Mohs' Scale Is Still Used in Mineralogy & Gemmology Crude but Practical In 1822, Friedrich Mohs, a German mineralogist devised a crude but practical method of comparing hardness or scratch resistance of minerals. It has become universally known as Mohs scale or Moh's scale as the grammatically challenged would call it, actually it should properly be called Mohs' scale. 10 9 8 7 6 5 4 3 2 1 Diamond Corundum Topaz Quartz Feldspar Apatite Fluorspar Calcite Gypsum Talc Like , has a cycle too! • Virtually all of the water on earth has been here since the planet was born. • The water cycle continuously uses and replenishes available water. • Three parts of cycle: - Evaporation - Condensation - Precipitation • Three main types of water: - Salt Water (Oceans) - Frozen Water (Ice Caps and Glaciers) - Fresh Water Parts of Cycle • Evaporation Sun heats water, turning it into water vapor. • Transpiration Water vapor is released from leaves of plants and breathing of humans and other animals. • Condensation Water vapor condenses, forming clouds. • Precipitation Condensed water particles form droplets that fall to Earth. • Salt Water – 97% Found mainly in Oceans • Frozen Water – 2% Found in Ice Caps and Glaciers • Fresh Water – Less than 1% Found mainly in rivers, streams, and ponds. • Cover ¾ of Earth’s surface • Average 3 miles deep • The deeper the ocean the colder and saltier it gets. • Pressure increases as water depth increases. • Most recent “ice age” was 20,000 yrs ago. • At one time 5% of water, now 2%, so what happened? • There is floating ice in the form of icebergs, ice shelves, and Arctic Sea ice.. • And continental ice in the form of glaciers and ice sheets found in Greenland and Antarctica… • What would be more detrimental to our coastlines, melting floating ice or melting continental ice? • Only a small amount of Earth’s water is available as fresh water, in fact…less than 1% is fresh water. • Of that 1%... - 99% goes into underground reservoirs known as aquifers - It may take thousands of years for aquifers to fill up and just as long for humans to “tap” them to get fresh water. - Unfortunately seen by many humans as a resource that can be used with little regard for long-term consequences or contamination. The also has cycles… Air circulates just as rocks and water does. It consists of layers that differ in temperature and pressure. - Pressure decreases as distance from the Earth increases. - Temperature fluctuates throughout the atmosphere. • A “short-term” cycle = Weather • A “longer-term” cycle = Seasons • A “much longer-term” cycle = Climate Formation of the • Formed during planetary “degassing” – gasses like carbon dioxide, water vapor, sulphur dioxide and nitrogen were released from the interior of the Earth through processes like volcanic activity. Gas Composition of Earth's atmosphere: Nitrogen - 78% of atmosphere Oxygen - 21% of atmosphere Trace gases - 1% - Neon, Helium, Hydrogen, Methane, Carbon Dioxide Convection causes weather – the troposphere is a giant convection system powered by solar energy. Prevailing Westerlies = surface winds that blow west-to-east in the temperate regions of the northern and southern hemispheres Eaterlies = winds that blow east-towest in equatorial regions Doldrums = stagnant air at the equator Earth rotation stretches convection currents into three large east-west convection cells. Spring Summer Fall (Autumn) Winter Seasons result due to the tilt of the Earths axis. Climate is the average and variations of weather in a region over long periods of time. "Are we barreling down a runaway route toward climatic catastrophe, or will the future bring relatively benign changes that will not threaten society? The accumulation of greenhouse gases in the atmosphere will almost certainly cause Earth's surface temperature to rise. But we do not know how quickly the planet will warm or how that warming will affect different regions of the globe. Answers to such questions will only come through intense research into the mysteries of Earth's climate system." -- from Reports to the Nation on Our Changing Planet Scientists use the climate from many years ago and the current climate changes to determine what future climates will be. Resources http://www.worldclimate.com/ Website allows you to search for the climates throughout the world. http://www.teachersdomain.org/ Teacher’s Domain Video and Interactive Resources http://streaming.discoveryeducation.com/index.cfm Discover Education United Streaming Video http://www.usgs.gov/ US Geological Survey, Thristin’s Water Cycle Interactive http://www.climate.noaa.gov/about_climate/ NOAA Website, Climate Quote and Info http://www.science-teachers.com/earth.htm Earth Science Teaching Resources http://www.livetext.com/doc/3195583/16341175/ Link to my LiveText website and PowerPoint Presentation (Under “What’s Up This Week”) Science Matters Textbook