Ch. 3 The Dynamic Earth

 Earth is a system with 4 parts  Geosphere – rock  Atmosphere – air  Hydrosphere – water  Biosphere – living things  These 4 parts are constantly causing the earth to change.

 Composition of the earth – 3 layers  Crust – outer layer, thin, made of lighter elements  Mantle – middle layer, medium density rocks  Lithosphere – rigid outer layer made of tectonic plates  Asthenosphere – layer of rock that flows very slowly allowing the tectonic plates to move on top  Core – innermost layer of dense elements  Outer core – liquid nickel and iron  Inner core – solid nickel and iron

 Lithosphere divided into pieces called plates  Plates float on top of the asthenosphere  Continents are on top of plates and move with them  Plate boundaries – site of geological activity when plates collide, move away from or slide along each other  Causes mountain building, earthquakes, and volcanoes

 Fault – break in the earth’s crust where blocks of the crust slide along each other  Rocks (blocks) slip due to stress sending out vibrations of energy through the earth’s crust causing an earthquake  Magnitude – measure of energy released by an earthquake  Richter scale – 1 to 14 – measure of 7 = widespread damage  Where? – along plate boundaries  Can’t predict when, but can label hazard areas

 Volcano – mountains built by magma, rises from inside the earth to the surface  Located along plate boundaries  Ring of Fire – around pacific ocean  Effects: human loss, building destruction, crop destruction, mudflows, breathing difficulties, can cause climate changes

 Erosion – removal and transport of surface materials  Caused by wind and water  Changes the shape of rocks and landscape – softer rocks erode more quickly  Applachian mtns = rounded tops = older  Rocky mtns = jagged = younger

 Mixture of gases surrounding the earth  Keeps the earth warm so living things can survive  Gases constantly put in and taken out  Composition  Nitrogen 78%  Oxygen 21%  Other 1%  Atmospheric dust  Air Pressure – atmosphere more dense near surface due to gravity

 Based on temp changes  Troposphere – nearest to the surface, where all the weather occurs, temp ↓ as altitude ↑  Stratosphere – temp ↑ as altitude ↑ because ozone is absorbing uv rays from the sun  Mesosphere – coldest layer  Thermosphere - contains the auroras

 Energy comes from the sun  Transferred in 3 ways  Radiation – rays through space  Conduction – objects touching  Convection – by air currents – circulates heat through atmosphere Energy comes into atmosphere from sun  Some is reflected by earth’s surface  Some is absorbed by earth’s surface (1/2)  Some is scattered by clouds and air  Some is absorbed by clouds  Earth’s surface radiates heat back into atmosphere  Heat absorbed by greenhouse gases keeping the earth warm

 Process in which gases trap heat near the earth  Life could not exist on earth without GE

 All water on or near the earth’s surface  Required for life  The water cycle – continuous movement of water into the air, onto land and back to water sources  Evaporation – liquid to gas – ground to air  Condensation – gas to liquid – water forms droplet on dust particle – forms clouds  Precipitation – water falling from clouds

 World ocean – interconnected body of all the oceans  Covers 70% of earth’s surface  Made of: Pacific, Atlantic, Indian, Arctic  Ocean water: contains more salts than freshwater  Salinity – concentration of salts (avg. = 3.5%), different for different parts of the ocean  Temperature zones – warmer at the surface, colder in deep water  Function of world ocean – regulates temperatures in the atmosphere  Ocean water absorbs radiation from the sun and releases heat (more slowly than land)  Temp of atmosphere changes more slowly because of the ocean

 Ocean currents – stream like movements of water through the ocean, can be warm or cold, at the surface or deep  Warm water won’t mix with cold so the currents can travel a great distance where they influence local climates on land

 30% of hydrosphere – most is frozen in glaciers and icecaps, the rest is in rivers, lakes, wetlands, and the ground  River system – network of streams that drain an area of land  Groundwater – water stored underground in rock or soil (aquifers)

 Narrow layer around the earth’s surface in which life can exist  Includes uppermost part of geosphere, most of the hydrosphere, and the lower part of the atmosphere  Fulfills 3 requirements for life:  Liquid water, moderate temps, energy source  Energy flow  Closed system – energy comes in and goes out so it must be constantly supplied  Matter is recycled through the system