Geology 101 539 Class 1 Test 1 Tuesday September 2 14 Geology 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 First 3 exams are about 20 30 questions Final is about twice as many questions Final repeats questions from previous exams concepts Chapter 1 The Earth System What 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 Nile River Egypt Pahoeoe Lavas Hawaii rocks from it once being covered underwater The Scientific Method Physical events have rational explanations Good theories are simple and make predictions Theories not consistent with observations need to be modified The Scientific Method Process Flow Diagram Observations and Experiments Hypothesis Supported o No Revise and form other hypothesis o Yes move on to theory Theory Supported o No revise and start back at theory o Yes move on to the scientific model Scientific Model Example 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 A Vast range of length scales o From very short minutes o To very long billions of years o 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 Canyon o It took more than 250 million years to deposit this o The rocks at the bottom of the canyon are about 2 billion sequence of rocks years old A Rapid Geological Event Meteor Crater AZ James Hutton 1726 1797 o This feature 2 km across formed in less than one minute about 50 000 years ago The present is the key to the past We can reconstruct geological history since Earth has been o The Principle of uniformitarianism 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 0 Earth s Models Continents float like icebergs Dense iron core explains mass of Earth Earth s Major Layers By Composition Crust Mantle o 0 40 km o 0 4 of earth s mass o 40 2890 km o 67 1 of earth s mass o 2890 5150 km o 30 8 of earth s mass Solid Iron Inner Core o 5150 6370 km Liquid Iron Core Chemical Composition Whole earth Crust o Fe O Si MG 93 o 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 Geosystem o A specialized subsystem of the Earth system that encompasses specific types of terrestrial behavior Example 1 The Plate Tectonic System Boiling Water 1 Convection moves hot water from the bottom to the top 2 Where is cools moves laterally sinks 3 Warms and rises again Actual Earth 4 Hot matter from the mantle rises 5 Causing plates to form and diverge 6 Where plates converge a cooled plate is dragged under the 7 Sinks warms and rises again neighboring plate Example 2 The Geodynamo System Bar Magnet Electromagnetic Geodynamo