“Scientific” Thinking GLG 101 - Physical Geology Bob Leighty.

““Scientific” ThinkingScientific” Thinking

GLG 101 - Physical GeologyGLG 101 - Physical Geology Bob LeightyBob 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, email Dr. Bob if you have any questions about today’s lecture ([email protected]).Leave no questions behind!

Explore and have fun!Explore and have fun!

Geologic ThinkingGeologic Thinking

Misconception: Geology is not a science like physics or chemistry     

Fact: Any science is distinguished by its methodology in arriving at answers

Geology uses the scientific method in asking questions about the Earth

““Scientific”Scientific”

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An overturned fold in an outcrop Overturned folds in a diagram

Logical ThinkingLogical Thinking

The scientific method involves:

explaining & predicting (formulating hypotheses)  

testing the hypotheses   

We typically form several hypotheses for most problems

hypothesis theory !

We employ the “scientific method” everyday

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making observations  

Young Earth scientists observing their world at Red Mountain, Arizona.

Logical ThinkingLogical 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?Car Trouble?

Flat car/truck tire

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I ran over something sharp

Logical ThinkingLogical Thinking

Sail a ship and see what happens

2) Hypotheses (multiple)  

Flat Earth?Flat Earth?

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1) Observation

The Earth is flat

The Earth is round

3) Test

Ships disappear over the horizon

Beyond the horizon, there be dragons!

Logical ThinkingLogical Thinking

Collect data that links causes with effects

2) Hypotheses (multiple)   

Global Warming?Global Warming?

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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 ThinkHow We Usually Think

We may jump to conclusions with very little data

We like certainty (B&W situations) where none may exist

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Better ThinkingBetter 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

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Continental DriftContinental 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   

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Continental DriftContinental Drift

2) Hypothesis

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Continents move over time & were once part of a massive supercontinent (Pangea or Pan-gee-ah)   

A paleoreconstruction of Earth’s surface ~260 Ma (million years ago).

Earth’s surface today.

Continental DriftContinental Drift

3) Test

Could not be tested at the time (1915) - driving mechanism unknown

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Alfred Wegener The last picture of Wegener

Sea Floor SpreadingSea Floor Spreading

1) Observations (early 1960’s)

Sea floor is older/colder/lower away from mid-ocean ridges

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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 SpreadingSea Floor Spreading

2) Hypothesis

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New oceanic crust is created at mid-ocean ridges (MORs)

Magnetic polarity “stripes” formed as result of sea floor spreading

Sea Floor SpreadingSea Floor Spreading

3) Test

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Collect more data (age, composition, geophysical,

etc.) from the sea floor

An unmanned submersible.

Age distribution of the oceanic crust(red = youngest).

Plate TectonicsPlate Tectonics

1) Observations (1960’s)

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Large amounts of seismic, volcanic, and geophysical data   

Global distribution of earthquakes. An active Hawaiian volcano.

Plate TectonicsPlate Tectonics

2) Hypothesis

Earth’s outer layer is divided into many strong lithospheric plates that move and interact with each other

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Plate TectonicsPlate Tectonics

3) Test

Image the plates & Earth’s interior using seismic reflection, refraction, and tomography

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Directly measure rates of plate movement using lasers & GPS

WWW Links in this LectureWWW Links in this Lecture““Scientific”Scientific”

ThinkingThinking

> Science - http://en.wikipedia.org/wiki/Science

> Scientific method - http://en.wikipedia.org/wiki/Scientific_method

> Hypotheses - http://en.wikipedia.org/wiki/Hypotheses

> Flat Earth - http://en.wikipedia.org/wiki/Flat_Earth

> Continental Drift - http://en.wikipedia.org/wiki/Continental_Drift

> Pangea - http://en.wikipedia.org/wiki/Pangaea

> Alfred Wegener - http://en.wikipedia.org/wiki/Alfred_wegner

> Sea Floor Spreading - http://en.wikipedia.org/wiki/Sea_floor_spreading

> Mid-ocean Ridge - http://en.wikipedia.org/wiki/Mid-ocean_ridge

> Plate Tectonics - http://en.wikipedia.org/wiki/Plate_tectonics

> Lithosphere - http://en.wikipedia.org/wiki/Lithosphere

> Seismic reflection - http://en.wikipedia.org/wiki/Seismic_reflection

> Seismic refraction - http://en.wikipedia.org/wiki/Seismic_refraction

> Seismic tomography – http://en.wikipedia.org/wiki/Seismic_tomography

> GPS - http://en.wikipedia.org/wiki/GPS