“Scientific” Thinking GLG Physical Geology Bob Leighty

These notes and web links are your primary “lecture” content in this class. Additionally, various articles are assigned each week to supplement this “lecture” information. I believe you’ll have enough information to reference without having to purchase a costly textbook. These lecture notes are very similar to the ones I use in my traditional classes. You’ll find they are loaded with imagery and streamlined text that highlight the most essential terms and concepts. The notes provide a framework for learning and, by themselves, are not meant to be a comprehensive source of information. To take advantage of the global knowledge base known as the Internet, I have included numerous hyperlinks to external web sites (like the Wikipedia, USGS, NASA, etc.). Follow the links and scan them for relevant info. The information from linked web sites is meant to supplement and reinforce the lecture notes – you won’t be responsible for knowing everything contained in them. As a distance learning student, you need to explore and understand the content more independently than in a traditional class. As always, I will help guide you through this learning adventure. Remember, Dr. Bob if you have any questions about today’s lecture Leave no questions behind! Explore and have fun!

Geologic Thinking  Misconception: Geology is not a science like physics or chemistry science  Fact: Any science is distinguished by its methodology in arriving at answers  Geology uses the scientific method in asking questions about the Earthscientific method “Scientific” Thinking An overturned fold in an outcrop Overturned folds in a diagram

Logical Thinking  The scientific method involves: explaining & predicting (formulating hypotheses) hypotheses testing the hypotheses  We typically form several hypotheses for most problems  hypothesis  theory !  We employ the “scientific method” everyday “Scientific” Thinking making observations Young Earth scientists observing their world at Red Mountain, Arizona.

Logical Thinking 1)Observation  A wild animal bit into it 3)Test 2)Hypotheses (multiple)  Look at the tire  Old, neglected tire just wore out Car Trouble?  Flat car/truck tire “Scientific” Thinking  I ran over something sharp

Logical Thinking  Sail a ship and see what happens 2)Hypotheses (multiple) Flat Earth? “Scientific” Thinking 1)Observation  The Earth is flat  The Earth is round 3)Test  Ships disappear over the horizon  Beyond the horizon, there be dragons!

Logical Thinking  Collect data that links causes with effects 2)Hypotheses (multiple) Global Warming? “Scientific” Thinking 1)Observation  Anthropogenic (humans are doing it)  Heliogenic (the sun’s doing it)  Other 3)Test  Mean global temperatures have risen over time

 We relate new info to existing perceptions How We Usually Think  We may jump to conclusions with very little data  We like certainty (B&W situations) where none may exist “Scientific” Thinking

Better Thinking  Question assumptions (don’t always take things for granted)  Try to separate what you know from what you assume (ask: how do I/they know that?)  Look at concepts from several points of view “Scientific” Thinking

Continental Drift 1)Observations (1915)  Similar land fossils of different continents  “Jigsaw puzzle fit” of the southern continents  Matching rock types and features on separate continents “Scientific” Thinking

Continental Drift 2)Hypothesis “Scientific” Thinking  Continents move over time & were once part of a massive supercontinent (Pangea or Pan-gee-ah) Pangea A paleoreconstruction of Earth’s surface ~260 Ma (million years ago). Earth’s surface today.

Continental Drift 3)Test  Could not be tested at the time (1915) - driving mechanism unknown “Scientific” Thinking Alfred WegenerThe last picture of Wegener

Sea Floor Spreading 1)Observations (early 1960’s)  Sea floor is older/colder/lower away from mid-ocean ridges “Scientific” Thinking  Various data describing the layout, age, composition, and geophysical make-up of the sea floor Magnetic anomalies on the seafloor southwest of Iceland. A 3D topographic map of part of a mid-ocean ridge.

Sea Floor Spreading 2)Hypothesis “Scientific” Thinking  New oceanic crust is created at mid-ocean ridges (MORs)mid-ocean ridges Magnetic polarity “stripes” formed as result of sea floor spreading

Sea Floor Spreading 3)Test “Scientific” Thinking  Collect more data (age, composition, geophysical, etc.) from the sea floor An unmanned submersible. Age distribution of the oceanic crust (red = youngest).

Plate Tectonics 1)Observations (1960’s) “Scientific” Thinking  Large amounts of seismic, volcanic, and geophysical data Global distribution of earthquakes.An active Hawaiian volcano.

Plate Tectonics 2)Hypothesis  Earth’s outer layer is divided into many strong lithospheric plates that move and interact with each otherlithospheric “Scientific” Thinking

Plate Tectonics 3)Test  Image the plates & Earth’s interior using seismic reflection, refraction, and tomographyreflection refractiontomography “Scientific” Thinking  Directly measure rates of plate movement using lasers & GPSGPS

WWW Links in this Lecture “Scientific” Thinking > Science - > Scientific method - > Hypotheses - > Flat Earth - > Continental Drift - > Pangea - > Alfred Wegener - > Sea Floor Spreading - > Mid-ocean Ridge - > Plate Tectonics - > Lithosphere - > Seismic reflection - > Seismic refraction - > Seismic tomography – > GPS -