Chapter 3 The Dynamic Earth

1. Chapter 3The Dynamic Earth

2. Four “spheres” of Earth: Earth is an integrated system in which all of these parts interact with each other: Geosphere + Atmosphere + Hydrosphere + Biosphere = Earth The earth is constantly changing.

3. Geosphere Definition: the solid part of the Earth that consists of all rock and the soils and sediments on Earth’s surface Three basic layers: crust, mantle, core

4. Geosphere More detailed layers: Lithosphere – crust plus rigid upper mantle Asthenosphere made up of rock that flows very slowly Mesosphere Outer core Inner core (see pg. 61)

5. Lithosphere Consists of crust and outermost rigid layer of mantle Divided into tectonic plates – huge pieces of the earth that slowly glide across the underlying asthenosphere, continents are located on tectonic plates and move around with them, called theory of continental drift (proposed by Alfred Wegener in 1912, not accepted until 1950s) http://videos.howstuffworks.com/hsw/12651-our-restless-planet-plate-tectonics-and-pangaea-video.htm

6. Learn the names of these tectonic plates!

7. Plate boundaries At plate boundaries, there is a lot of activity! • Mountain formation (Ex: Himalayas) – between the Eurasian and Indian plates, presence of mountains influences life forms present (due to factors such as elevation, rain shadow, etc.)

8. 2. Earthquakes occur tectonic plate boundaries (Ex: California’s San Andreas Fault – a break in the earth’s crust)

9. Earthquakes • Earthquakes occur along fault lines – breaks in the Earth’s crust. • Earthquakes are measured on the Richter scale. • The smallest earthquake that can be felt is a magnitude 2.0. The largest ever recorded was a 9.5 magnitude earthquake. • Earthquakes can occur almost anywhere.

10. What are some environmental effects of earthquakes? slope movements ground cracks ground settlements surface waves/tsunamis

11. Not worried about earthquakes in Hoover, Alabama? Ever heard of the New Madrid Fault Line?

12. Section 1 – The Geosphere 3. Volcanoes • Volcanoes are built from magma –melted rock. • Volcanoes are often located near tectonic plate boundaries. • Volcanoes can occur under the sea as well as on land, can form islands such as the Hawaiian Islands

13. “Ring of fire” – many volcanoes are found around the Pacific plate boundary

14. Local effects of volcanoes: • lava flow may engulf and bury the land, but new soil and vegetation eventually develop • volcanic ash slowly weathers to form rich, loamy soils. • Global effects of volcanoes: • clouds of volcanic ash and sulfur-rich gases can reach the upper atmosphere and reduce amount of sunlight that reaches earth (ex. Tambora 1815, “the year without a summer”)

15. Mt. St. Helen’s, Washington, 1980 On May 18th, an earthquake measuring 5.1 on the Richter scale caused a landslide on the northern flank of the volcano, which in turn exposed the crypto dome below, resulting in a sudden release of pressure and a cataclysmic eruption in the form of a lateral (sideways) blast. The blast zone consisted of 230 square miles with the eruption leaving a 'lunar' landscape in its wake. The effects of the eruption included:*Released equivalent of 500 atomic bombs* 57 people died in the eruption - most from poisonous gases;* large number of wildlife were killed by the blast and the volcanic ash with nothing surviving in the blast zone* flooding resulting from blocked rivers washed away road and rail bridges* crops were ruined and livelihoods of loggers were devastated with large areas of trees being flattened like matchsticks.

17. Erosion Definition: removal and transport of the Earth’s surface material by a natural agent, such as wind, water, ice or gravity Large scale: Grand Canyon, Yosemite valley

18. Erosion Often made worse by human activities, such as deforestation Plane view of deforestation-induced erosion in Madagascar

19. Section 2 – The Atmosphere • Atmosphere – mixture of gases that surround the Earth; these gases include: • Nitrogen – 78% • Oxygen – 21% • Carbon dioxide, water, methane – 1%

20. Functions of the atmosphere 1. Greenhouse effect makes life possible – the process by which gases in the atmosphere trap heat near Earth • This is a NATURAL process. • Major greenhouse gases are water vapor, carbon dioxide, methane, CFC’s 2. Protects life on earth from radiation, objects from space 3. Part of the cycling of water, carbon, and nitrogen which are necessary for life

21. Layers of the atmosphere What layers of the atmosphere do you think we will focus on in Environmental Science? Why?

22. Section 2 – The Atmosphere • Energy from the sun is transferred to the Earth’s atmosphere in 3 ways • Radiation – the transfer of energy across space • Conduction – the flow of heat from a hot object to a cold object when the two objects touch • Convection – the transfer of heat by air currents See pages 70-71 in textbook.

23. Section 3 – The Hydrosphere and Biosphere • The Hydrosphere and Water Cycle • Hydrosphere – all the water on or near the Earth’s surface • Water cycle – continuous movement of water into the air, onto land, and then back to water sources

24. Section 3 – The Hydrosphere and Biosphere • Steps of the water cycle • Evaporation – liquid water is heated by the sun and then rises into the atmosphere (steam or humidity) • Condensation – water vapor forms water droplets on dust particles and form clouds or fog • Precipitation – large droplets fall from clouds in the form of rain, snow, sleet, or hail

25. Section 3 – The Hydrosphere and Biosphere • Earth’s Oceans • The Earth’s oceans cover over 70% of the Earth’s surface • Ocean water – contains much more salt than fresh water • Salinity – the amount and concentration of salt in ocean water • Temperature zones • There are 3 different temperature zones in the ocean

26. Hydrosphere Temperature zones in ocean: Surface – much light, warmest Thermocline – steep drop in temperature Deep zone – no light, very cold

27. Section 3 – The Hydrosphere and Biosphere • A Global Temperature Regulator • One of the most important functions of the ocean is to absorb and store energy from the sun • This function is what regulates the temperature of the Earth

28. Section 3 – The Hydrosphere and Biosphere • Ocean Currents • The ocean has movements of water similar to streams called currents. There are 2 different types of ocean currents. • Surface currents – occur near the surface of the ocean; they are driven by the wind • Deep currents – occur near the floor of the ocean; they are very slow moving and COLD

29. Section 3 – The Hydrosphere and Biosphere • Fresh Water – contains very little salt • Icecaps and glaciers • Rivers, lakes and wetlands • Groundwater • Aquifers

30. Biosphere • The Biosphere – the narrow layer around Earth’s surface in which life can exist • Requirements for life as we know it: • Liquid water • Temps between 10°C and 40°C • Source of energy (sunlight in most cases, but chemical energy is another source) • Materials needed for growth must be cycled, through air, water, earth and organisms

31. Closed vs. Open System • Closed system: • Matter cannot enter • Energy does enter • Open system: • Matter can enter • Energy can enter Which type of system is this?