Geology 101-539Class 1-Test 1Tuesday, September 2, 14Geology 101 In A Nutshell- 24 Lectures- 11 Lab Practices- 4 Lecture exams (including final)Course Outline- look on syllabus - Midterm 1: Chapters 1-6, September 30,2014- Midterm 2: Chapters 7-11, October 15,2014- Midterm 3: Chapters 12-17, November 6, 2014- Book is very important - Know concepts and details- Look at chapter summaries and details and chapter terms and concepts- First 3 exams are about 20-30 questions- Final is about twice as many questions- Final, repeats questions from previous examsChapter 1: The Earth SystemWhat are the main features of Earth’s surface?- Blue Color- Various depth below sea level- Green-Red- Various elevation above sea level- Oceans are smooth usually, unless the have underlying elevation. If there are mountains under the water or other different elevations, it is a rougher surface- Earth’s topography is measured with respect to sea level- There is about 20 km, between the highest point on earth (Mt. Everest) to the lowest point on earth (Marianas Trench)Geologists Study Earth’s Natural Wonders- Hot Springs, Yellowstone National Park- Himalayas Range- Top of Mt. Everest, you will find fossils in the rocks from it once being covered underwater. - Nile River, Egypt- Pahoeoe Lavas, HawaiiThe Scientific Method…- Physical events have rational explanations- Good theories are simple and make predictions- Theories not consistent with observations need to be modifiedThe Scientific Method Process Flow Diagram- Observations and Experiments- Hypothesis- Supported?o No- Revise and form other hypothesiso Yes- move on to theory- Theory- Supported?o No- revise and start back at theoryo Yes- move on to the scientific model- Scientific ModelExample of an Early Scientific Achievement- Eratosthenes in 250 B.C. determined Earth’s size (circumference 40,000 km)- He heard that Alexandria cast a shadow at a certain degree (70 degrees). He didn’t agree that the earth was flat. He studied shadows and said that if the earth is flat then the shadow would be the same everywhere. He paid a guy to walk and count the number of steps, he measured 800 km. The science of Geology involves…- A vast range of time-scales:o From very short (minutes)o To very long (billions of years)- A Vast range of length-scaleso From very short (mineral grains)o To very long (continents, oceans)- Geologists work outside using earth as a natural laboratory A Slow Geologic Event- The Grand Canyono It took more than 250 million years to deposit this sequence of rocks.o The rocks at the bottom of the canyon are about 2 billion years old. A Rapid Geological Event- Meteor Crater, AZo This feature (2 km across) formed in less than one minute about 50,000 years ago.James Hutton (1726-1797)- “The present is the key to the past”o The Principle of uniformitarianism- We can reconstruct geological history since Earth has been shaped by the same geological processes that we observe today.Earth’s Bulk Parameters- Mass (10^24 kg) 5.9736- Volume (10^10 km^3) 108.321- Equatorial Radius (km) 6378.1- Volumetric Mean Radius 6371.0- Ellipticity (flattening) 0.00335- Mean Density (kg/m^3) 5515.0Earth’s Models- Continents “float” like icebergs- Dense iron core explains mass of EarthEarth’s Major Layers…By Composition- Crusto 0-40 kmo 0.4% of earth’s mass- Mantleo 40-2890 kmo 67.1% of earth’s mass- Liquid Iron Coreo 2890-5150 kmo 30.8% of earth’s mass- Solid Iron Inner Coreo 5150-6370 kmChemical Composition- Whole eartho Fe+O+Si+MG=93%- Crusto Si+O+Al=82%How Planet Earth Works?...- In order to understand such a complex system, geologists think about the Earth as a collection of open subsystems, some of them interacting with each other- Geosystemo A specialized subsystem of the Earth system that encompasses specific types of terrestrial behaviorExample 1: The Plate Tectonic System- Boiling Water1. Convection moves hot water from the bottom to the top…2. …Where is cools, moves laterally, sinks…3. …Warms, and rises again- Actual Earth4. Hot matter from the mantle rises…5. …Causing plates to form and diverge6. Where plates converge, a cooled plate is dragged under the neighboring plate…7. …Sinks, warms, and rises again.Example 2: The Geodynamo System- Bar Magnet- Electromagnetic-