Environmental Science

1. Environmental Science Chapter 3 Section 1

2. Earth • Earth is an integrated system that consists of rock, air, water, living things all interacting together • Geosphere- rock • Atmosphere- mixture of the gases we breathe • Hydrosphere- all the water • Biosphere- part of E where life exists

3. Geosphere • The geosphere is the part of E consisting of all rock, solids, and sediments on E’s surface. • Geologists study E’s interior by using seismic waves • Same wave that travel through E during earthquake • Seismic waves work in the same way tapping a melon to test for ripeness tells us about the contents of the inside based on the type of sound that we hear

4. Geosphere • Seismic waves are altered by the nature of materials it travels through • Seismologists measure changes in speed and direction of seismic waves • Seismologists have learned that E is composed of different layers and have inferred what substances make up those layers • The 3 layers of the E are: crust, mantle, core

5. Crust • The crust is the thin outer layer made almost entirely of “light” elements • Responsible for less than 1% of planet’s mass • 5-8 km thick beneath the ocean • 20-70 km thick beneath the continents

6. Mantle • The mantle lies beneath the crust • Responsible for 64% of the planets mass • 2900 km thick • Made of rocks of medium density

7. Core • The core is the innermost layer of the E. • Composed of the densest elements • Radius of 3400 km

8. Lithosphere • The E can be divided into 5 layers based on physical properties • Lithosphere • Outermost layer • Cool, Rigid • 15-300 km thick • Includes crust and upper mantle • Divided into tectonic plates

9. Tectonic Plates • Tectonic plates glide across underlying layer as ice drifts over a pond • Continents are on tectonic plates and move along with them • The major plates are: • Pacific • No. American • So. American • African • Eurasian • Antarctic

11. Tectonic Plates • Much of the geologic activity at the surface of E takes place at boundaries between plates • Forces produced at boundaries can form mountains, cause earthquakes, and erupt volcanoes • Mountain formation is caused by crust collisions and increase thickness giving mtn. ranges

12. Asthenosphere • The asthenosphere is the layer beneath the lithosphere • It is a plastic, solid layer of the mantle • Made of rock that flows very slowly and allows tectonic plates to move on top

13. Inner Layers • Mesosphere • Lower part of mantle • Outer core • Dense liquid layer • Inner core • More dense solid layer • Mostly iron and nickel • 4000-5000 degrees Centigrade • Despite heat, core is solid due to intense pressure

14. Earthquakes • A fault is a break in the Earth’s crust along which blocks of the crust slide relative to one another • When rocks under stress break along a fault, vibrations are set off • These vibrations of the E’s crust are earthquakes

15. Earthquakes • The Richter scale is used by scientists to quantify the amount of energy released by an earthquake • The measure of the energy released is called magnitude • Smallest magnitude measured is 2.0 • Magnitude of 7.0+ cause widespread damage • Largest magnitude ever recorded is 9.5 • Each increase of magnitude by one whole number indicates the release of 31.7 X more energy than the whole number before it.

16. Earthquakes • Earthquakes take place at or near tectonic plate boundaries due to large stresses generated when plates separate, collide, or slip past each other • Earthquakes are not limited to these boundaries • Scientists can not predict when or where earthquakes occur

17. Volcanoes • A volcano is a mountain built from magma (melted rock) which rises from E’s interior to the surface. • Often located near plate boundaries where plates are either colliding or separating from one another • Occur on land or in sea • Under the sea volcanoes may eventually break the surface as islands

18. Volcanoes • Local effects of volcanic eruptions can be • Ash • Bury crops • Collapse buildings • Damage car engines • Cause breathing difficulties • Dust • Gases • Mudflow from ash mixing with water

19. Volcanoes • Global effects of large volcanic eruptions can be • Clouds of ash and gases reaching the upper atmosphere • Ash can reduce the sunlight reaching E’s surface

20. Volcanoes • The largest observed volcanic eruption in the last couple centuries occurred in 1815 in Indonesia. The island was once 4000m tall but the volcano, Tambora, blew off a quarter of its height in it’s eruption. At the end of the 5-day eruption, he mountain had diminished to 2850m. The eruption killed 10000 people, ruined ag land, destroyed settlements. Explosion was so violent that debris shot 48km into the stratosphere and blocked 1/5 of solar energy that reached the E. The light and heat reduction was felt globally. It caused unusual weather patterns around the world and widespread crop failure. In some places, snow and frost occurred as late as June. This gave the year 1815 the name “the year without a summer”.

21. Erosion • Forces at the boundaries of plates bring rocks to the surface of the E • At the surface, rocks are altered by other forces • The removal and transport of surface material is called erosion • Erosion wears down rocks and makes them smoother • The older a mtn. range, the longer erosion has acted upon it. • Knowing this helps scientists gauge age of a mtn range. • The Appalachian Mtns. Are round-topped and deemed older than the jagged-topped Rocky Mtns.

22. Erosion • Water erosion • Erosion by rivers and oceans • Wind erosion • Places with few plants erode more quickly due to wind