THY DYNAMIC EARTH Geosphere, Atmosphere, Hydrosphere & Biosphere 1)Geosphere 2)Atmosphere 3)Hydrosphere 4)Biosphere 1) Geosphere Objectives Describe the composition & structure of the Earth Explain the main cause of earthquakes Identify the relationship b/w volcanic eruptions & climate change Describe how wind and water alter Earths surface What is the Geosphere? (ROCK) The solid part of Earth that consists of all rock, soils, and loose rock on Earths surface Avg. distance through the center of Earth to the other side = 12,756 km (7,926 miles) Composition of Earth 3 layers Crust thinnest layer, continents & ocean floor Type of rock: Silicon & Aluminum Mantle middle layer, 68% of Earths mass Type of rock: Iron & Magnesium Core innermost layer, center of the Earth Type of rock: Iron & Nickel Click on pic Structure of Earth 5 layers 1. Lithosphere outer layer & uppermost part of mantle, divided into tectonic plates 2. Asthenosphere solid layer of the mantle made of rock that flows very slowly & allows tectonic plates to move on top of it 3. Mesosphere Middle sphere, lower layer of mantle, very dense & solid 4. Outer Core outer shell of Earths core, made of liquid nickel & iron, dense liquid core 5. Inner Core dense & solid, ~ temp b/w 7232 o F 9752 o F Plate Tectonics The lithosphere is divided into pieces called tectonic plates that glide across the underlying asthenosphere. Plate Boundaries 3 Types 1. Convergent - oceanic plate is forced down into the mantle Example: Washington-Oregon coastline 2. Divergent extensional forces stretch the lithosphere producing a deep fissure Ex: Mid-Atlantic Ridge 3. Transform formed b/w 2 different plates that move away from the spreading center Ex: San Andreas Fault Now you try! Milky Way Activity Represent different faults/boundaries that we just discussed Turn in worksheet at end of class. 1) Geosphere Objectives Describe the composition & structure of the Earth Explain the main cause of earthquakes Identify the relationship b/w volcanic eruptions & climate change Describe how wind and water alter Earths surface Earthquakes How an earthquake is formed? A fault is a break in Earths crust along which blocks of the crust slide relative to one another Rocks under pressure suddenly slip along a fault & set off vibrations Vibrations of Earths crust caused by slippage along a fault are earthquakes Earthquakes cont. Quantify the amount of energy released by an earthquake The measure of the E released magnitude Smallest magnitude felt = 2.0 Largest magnitude felt = 9.5 Widespread damage = 7.0+ To increase one whole #, the earthquake must be 30x stronger Richter Scale Earthquakes cont. Take place/near tectonic plates San Andreas fault (entire length of California) 1886, ~7.0 Earthquake shook Charleston, SC Earthquakes Occur? Volcanoes Is a mountain built when magna (melted rock) rises from Earths interior to its surface Magma reaches surface = lava Located near tectonic plates boundaries Occur on land or under the sea (above ocean surface then islands are formed) Worlds most active volcanoes on land are surrounding the Pacific Ocean. Local Effects of Volcanic Eruptions Erupts when the pressure of magma inside becomes so great that is blows open the solid surface of the volcano Clouds of ash, dust, & gases can flow down the slope of a volcano at speeds up to 100mi/h & sear everything in its path Buildings collapse due to weight of ash, bury crops, & damage engines Breathing difficulties Pompeii Images In 79 A.D. Mount Vesuvius, a volcano near the Bay of Naples in Italy erupted buried the city of Pompeii World Effects of Volcanic Eruptions Change Earths climate for several years Reduce the amount of sunlight Lower the surface temperature Weathering & Erosion Pick up a sheet of white paper Divide the paper into 3s (like an envelope) On the top 1/3 DRAW/CREATE your own picture of a river (15 minutes) Weathering & Erosion Earths surface is continually changing by: Wind Running water Moving rocks Chemical Weathering: wears down rocks making them smoother as time passes Erosion: transports the materials elsewhere Erosion Rivers & Oceans Waves erode coastlines Rivers carve deep gorges in the landscape Colorado River Grand Canyon Wind blows soil away very quickly Beaches & deserts No plants in loose soil Soft rocks erode faster than hard rocks Water ErosionWind Erosion Erosion Landforms Water erosion Wind erosion