1. Introduction To Physical Geology Starring Professor Sean Tvelia

2. The Science ► Geology is typically broken up into two fields of study  Physical Geology  Historical Geology

3. Physical Geology ► Examines the materials composing Earth and seeks to understand the processes that operate beneath the surface  It is the how and why of Geology

4. Historical Geology ► Seeks an understanding of the origin of Earth and its development through time.  It is the who, what, where, and when

5. Why bother at all? ► Many of the problems and issues addressed by geology involve natural hazards, resources, world population and environmental issues.

6. The Scientific Method  Questions  Collection of Data  Development of Hypothesis  Testing of Hypothesis ► Science assumes the natural world is consistent and predictable ► Therefore our goal is to discover ‘ patterns ’ that we can then use to make predictions

7. Geology Through Time  Two major schools of thought ► Catastrophism ► Uniformitarianism  James Hutton ► Dynamic/Cyclic Concept of Earth History ► Used principle of actualism (uniformitarianism)

8. Earth as a System  Earth ’ s Four Spheres ► Atmosphere  The air we breathe ► Hydrosphere  The water we drink ► Biosphere  life ► Solid Earth  Where we live All of these spheres interact with each other. A minor adjusting In the properties of one could lead to drastic changes in the Properties of the other three

9. Power  External processes powered by the Sun  Atmosphere  Hydrosphere  Biosphere  The Earth system is also powered by Earth ’ s interior  Heat remaining from the formation of the planet and heat that is continually generated by radioactive decay powers: ► Volcanoes ► Earthquakes ► Mountain building

10. How did it all start ► Current belief is that the Earth and the entire solar system were born at relatively the same time.  All objects within our solar system were formed from an enormous cloud of gas and dust called a Nebula. ► Hence the name Nebula Hypothesis

11. Once upon a time …5 billion years ago ► This enormous cloud began to contract and spin  This contraction caused the nebula to spin faster (kind of like an ice skater spinning)  Eventually the inward contraction was balanced by the outward force of the spin ► This forced the nebula to take on a disc shaped appearance

12. Lets go to the video tape

13. Formation of Earth’s Layers ► As material accumulated to form the Earth, the high velocity impacts and decay of radio active elements caused the Earth’s temperature to steadily increase.  This heating caused the melting of many of the heavier elements: Iron, Nickel ► Heavier elements sank, lighter elements and compounds remained at the surface

14. Three principal compositional layers: ► Crust – the comparatively thin outer skin that ranges from 3 kilometers (2 miles) at the oceanic ridges to 70 kilometers (40 miles in some mountain belts) ► Mantle – a solid rocky (silica-rich) shell that extends to a depth of about 2900 kilometers (1800 miles) ► Core – an iron-rich sphere having a radius of 3486 kilometers (2161 miles)  Average density is nearly 11 g/cm3 and at Earth’s center approaches 14 times the average density of water  Mostly iron, with 5 to 10 percent nickel and lesser amounts of lighter elements

16. The surface of the Earth ► Earth surface has two obvious divisions  Continents ► Most prominent features are linear mountain belts and shields  Ocean Basins ► Ocean ridge system- the most prominent topographic feature on Earth ► Deep-ocean trenches ► Significant difference between the continents and oceans  One is Wet : )  their relative levels (how high is the ocean)