1. Earth’s Structure

2. Astronomer can see stars at the farthest edge of the universe using a telescope. Biologist can see the inner structure of cells using a microscope. No instrument that allows geologists to look deep inside Earth…light does not travel through most rocks.

3. So if we can’t see inside the Earth, how do we know what the interior is like? Scientist can listen to the Earth. Waves from earthquakes travel through the Earth like sound waves travel to our ears. Scientists can interpret these waves to learn about Earth’s structure.

4. The Science of Geology Geology = the study of planet Earth, including its composition and structure. Geologists = scientists who study Earth and the processes that have shaped the Earth over time.

5. Forces that Change the Earth’s Surface ConstructiveDestructive Shape the surface by building up mountains and other land areas. Slowly wear away mountains and eventually, every other feature on Earth’s surface

6. James Hutton http://www.usgs.gov/museum/575005.html Scottish physician and farmer Observed that some rock were made of particles that came from older rocks Realized that Earth’s surface had changed over time. Uniformitarianism = the idea that the geologic processes that occur today, also occurred in the past

7. A Cross Section of Earth Earth Crust Mantle Core Egg Shell Egg White Yolk finecooks.com

8. sciencelearn.org.nz

9. The Crust The rocky outer layer of the Earth Thin compared to the other layers Made up of silicates (rocks made of silicon & oxygen) Two types: continental & oceanic

10. Continental Crust Oceanic Crust Makes up continents Less-dense rock (granite) Averages 40 km thick (8-75km) Thickest under mountain chains Makes up ocean floor Dense rock (basalt) 7 km thick

11. The Mantle Beneath crust Layer of hot, solid rock Extends 2850 km Pressure and temperature increase with depth Composed of mostly silicates, Fe, Mg Denser than crust 3 layers

12. 3 Layers of Mantle Lithosphere = relatively cool, rigid rock. Includes the uppermost part of mantle & crust Asthenosphere = softer, weaker rock that can flow slowly (taffy) Mesosphere = stronger, stiffer rock. Extends to upper surface of core.

13. The Core A large sphere of metal that occupies Earth’s center Mostly composed of Fe Pressure increases with depth Estimated 3.6 million times the pressure at surface Two parts: outer core & inner core

14. Outer CoreInner Core High temperatures keep metal liquid Earth’s rotation/ flowing iron produces electric current and creates Earth’s magnetic field Very high pressure results in a solid inner core

15. REVIEW

16. Question #1 A scientist that studies the Earth and the processes that have shaped the Earth is a __________________.

17. Question #2 Uniformitarianism is the idea that the geologic processes that operate today also operated ____ ____ _________.

18. Question #3 The Earth can be divided into three main layers. The _____________, the ______________ and the _______________.

19. Question #4 As the depth into the Earth increases, pressure and temperature _________________.

20. Question #5 Which part of the Earth’s core is liquid?