Course description Geology lab - Centralia College ... Mount Hood volcano Tree buried by past lahar …and geology studies past history of the Earth Mount Rainier volcano, from the

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Introduction to GeologyIntroduction to Geology

Patrick PringlePatrick PringleInstructor, NSC 318fInstructor, NSC 318fppringleppringle via via centralia.educentralia.edu360360--736736--9391 x550 9391 x550

Earth Science web page:

www.centralia.eduwww.centralia.edu/academics/earthscience/index.html

Websearch: Earth science Centralia

Course descriptionCourse description

PHYSICAL GEOLOGY (4)PHYSICAL GEOLOGY (4)Explore earth materials, processes and Explore earth materials, processes and structures within a plate tectonics framework: structures within a plate tectonics framework: origin and structure of the earth, rocks and origin and structure of the earth, rocks and minerals, geologic time, fossils and evolution, minerals, geologic time, fossils and evolution, earthquakes and volcanoes, ocean basins, earthquakes and volcanoes, ocean basins, formation of landscapes, special topics. formation of landscapes, special topics.

Geology labGeology lab

Learn how to recognize earth materials, Learn how to recognize earth materials, features, and structures. Identification of features, and structures. Identification of common rocks and minerals; topographic and common rocks and minerals; topographic and geologic maps. geologic maps.

OutcomesOutcomesImproved quantitative reasoning skills as they pertain Improved quantitative reasoning skills as they pertain to geology and solving geology problemsto geology and solving geology problemsImproved spatial reasoning skills as related to Improved spatial reasoning skills as related to geologic processes and materialsgeologic processes and materialsDevelop critical thinking skills in geologyDevelop critical thinking skills in geologyUnderstanding of geologic timeUnderstanding of geologic timeUnderstanding of the interconnectedness of Earth Understanding of the interconnectedness of Earth systemssystemsUnderstanding of the scientific method as it pertains Understanding of the scientific method as it pertains to geologyto geologyAbility to communicate geologic informationAbility to communicate geologic information

Mount St. Helens, February 1983

Geology studies active processes of the Earth

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Mount Hood volcano Tree buried by past lahar

…and geology studies past history of the Earth

Mount Rainier volcano, from the west

Geologists keep discovering new things! Our knowledge of Mount Rainier’s volcanic history has exploded in the past few decades.

Bonneville landslide—dammed the Columbia River in the mid 1400s

Geologic processes can be hazardous and can profoundly influence humans.

Geology has become interdisciplinary. These scientists are using the study of tree rings to estimate the age of a geologic landform.

• Why Study Earth? --We are seeing revolutionary changes in our understanding of the Earth, the environment, and the universe!

• Plate tectonics – the Earth’s machine: subduction, accreted terranes, etc--applications to geology of the planets…

• Interconnected Earth systems – rock, water, ice, atmosphere, biosphere…

• Geologic and environmental history

Why study Earth?Why study Earth?

1.11.1 What is geology?What is geology?1.2 Why study geology?1.2 Why study geology?1.3 How do we know 1.3 How do we know …… how to study Earth?how to study Earth?1.4 What does the principle of 1.4 What does the principle of uniformitarianismuniformitarianismmean?mean?1.5 What is the theory of plate tectonics?1.5 What is the theory of plate tectonics?1.6 How does the concept of work apply to 1.6 How does the concept of work apply to Earth?Earth?

Chapter 1 topics:Chapter 1 topics:

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Why study Earth?Why study Earth?Earth materials are the source (either directly or Earth materials are the source (either directly or indirectly) of all natural resourcesindirectly) of all natural resources–– Metals, plastics, timber, gemstones, building materials, etc.Metals, plastics, timber, gemstones, building materials, etc.

Why study Earth?Why study Earth?EarthEarth’’s surface is covered with soil that supports s surface is covered with soil that supports natural and agricultural plant diversitynatural and agricultural plant diversity

Why study Earth?Why study Earth?LandformsLandforms derived from Earth processes:derived from Earth processes:–– Provide the base for regional ecosystemsProvide the base for regional ecosystems–– Have aesthetic value to humansHave aesthetic value to humans

Fig 1.6mt

Why study Earth?Why study Earth?

And the #1 reason why we should study Earth:And the #1 reason why we should study Earth:

We all live on it!We all live on it!atmosphere

Hydrosphere (and cryosphere) Lithosphere

(geosphere)biosphere

What is geology?What is geology?gege··olol··oo··gygy ((Greek; geoGreek; geo-- + + --logi)logi)

The scientific study of the planet Earth,the materials of which it is made,

the processes that act on those materials,

the products formed,

and the history of the planet and its life forms since its origin (including human interactions)

Glossary of Geology, 2005, Neuendorf, Mehl, Jackson (Eds.)

1.1 What is geology?1.1 What is geology?

The classic divisionsThe classic divisions–– Historical Geology Historical Geology –– the study of physical, the study of physical,

chemical, and biological processes used to chemical, and biological processes used to interpret Earthinterpret Earth’’s past development s past development (ex: mountain (ex: mountain building, climate change, and the evolution of organisms as building, climate change, and the evolution of organisms as preserved in fossils)preserved in fossils)

–– Physical Geology Physical Geology –– (the subject of this text)(the subject of this text)

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The classic divisionsThe classic divisions–– Historical GeologyHistorical Geology–– Physical Geology Physical Geology –– (the subject of this text) arose (the subject of this text) arose

from study of landforms and how they came to be.from study of landforms and how they came to be.Today, geology touches on many other sciences Today, geology touches on many other sciences


Geologists study Earth from one extreme …

… to the other!

Fig 1.2a

And where is it practiced?


Processes are events that occur over time. This figure shows the different rates of Earth processes.

Fig 1.4

2237 mph2.237 mph1.1 What is geology?1.1 What is geology?

The interior of our Earth is layered. How have we detected and measured these layers??

Fig 1.3

One way to diagram the layers is by composition, and another way is by strength of the layers.

Geologic investigations produce maps and diagrams of Earth’s geologic materials.

Why study Earth?Why study Earth?Earth is host of the water used for: power, irrigation, Earth is host of the water used for: power, irrigation, consumption, recreation consumption, recreation

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1.2 Why study geology?1.2 Why study geology?Geologists map the risks of geologic hazards

Assessing the risks of hazards helps to make cities safer, like San Francisco.

Fig 1.5

Why study Earth?Why study Earth?Earth interacts with Earth interacts with humanityhumanity–– EarthquakesEarthquakes–– FloodsFloods

–– VolcanoesVolcanoes–– LandslidesLandslides

Electron Mudflow ~A.D. 1502Electron Mudflow ~A.D. 1502--33

Orting

Buried tree in Orting

Hazard zones for lahars, lava flows, and pyroclastic flows from Mount Rainier Hoblitt, R. P.; Walder, J. S.; Driedger, C. L.; Scott, K. M.; Pringle, P. T.; Vallance, J. W., 1998, Volcano hazards from Mount Rainier, Washington, revised 1998: U.S. Geological Survey Open-File Report 98-428, 11 p., 2 plates. [Accessed Feb. 11, 2002 at http://vulcan.wr.usgs.gov/Volcanoes/Rainier/Hazards/]

We can use geologic info to reduce risk to humans!

Climate change—What might be the effects on glaciers, fluvial and glacio-fluvial processes, erosion and aggradation patterns and rates, etc?

Geologic processes are an intrinsic part of past climate changes

The Scientific Method (in brief)The Scientific Method (in brief)–– Ask questions (based on observations and/or data)Ask questions (based on observations and/or data)–– Collect information (data)Collect information (data)–– Review and analyze data (your own and othersReview and analyze data (your own and others’’))–– State problemsState problems–– Formulate a hypothesisFormulate a hypothesis–– Test hypothesis for predictability and repeatabilityTest hypothesis for predictability and repeatability–– If tests refute If tests refute …… modify or make new hypothesismodify or make new hypothesis–– Publish results (refereed scientific journals)Publish results (refereed scientific journals)

1.3 How do we know 1.3 How do we know …… How to study Earth?How to study Earth?

Science is a process, not just a bunch of facts!

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How do geologists do science?How do geologists do science?–– The scientific method is not a recipeThe scientific method is not a recipe–– Different questions/scenarios require modification Different questions/scenarios require modification

of the methodof the methodField work Field work –– long the long the ““standardstandard”” of geologyof geologySeasonal processesSeasonal processesInstrumental/laboratory workInstrumental/laboratory workComputer simulationsComputer simulations


Geology is unique because of the scale and nature of its “natural laboratory”!

The The ““Big PictureBig Picture””–– Theories and Laws of NatureTheories and Laws of Nature


PrinciplesPrinciples (aka (aka ““LawsLaws””) ) –– universally applicable universally applicable generalizations that do not necessarily offer generalizations that do not necessarily offer explanationexplanationTheoriesTheories –– widely accepted explanationswidely accepted explanations of of natural phenomenanatural phenomena that that explain all relevant dataexplain all relevant datae.g. Theory of Plate Tectonics, Theory of Evolution by e.g. Theory of Plate Tectonics, Theory of Evolution by natural selection, Quantum theory etcnatural selection, Quantum theory etc

Theory – An explanatory system of propositions, general principles or laws, inferred from the phenomena and linking known facts and observations; held to be true until contradicted or amended by new facts or observations (from the Glossary of Geology, 2005)

The scientific methodThe scientific method integrates inquiry, integrates inquiry, explanation, and testability in understanding explanation, and testability in understanding natural phenomena.natural phenomena.Geologists use laboratory studies less often Geologists use laboratory studies less often than some scientists due to the rates and than some scientists due to the rates and scales of some Earth processes.scales of some Earth processes.

1.3 How do we know 1.3 How do we know …… How to study Earth?How to study Earth? 1.4 Uniformitarianism1.4 Uniformitarianism

What is it? What does it mean?What is it? What does it mean?–– Uniformity of natural processes as old as the Greek Uniformity of natural processes as old as the Greek

philosophersphilosophersMeans that the current processes on Earth obey the Means that the current processes on Earth obey the same basic physical laws they did same basic physical laws they did ““thenthen”” allowing us to allowing us to backback--calculate some prior condition.calculate some prior condition.

–– James Hutton and Charles Lyell (James Hutton and Charles Lyell (Principles of Principles of Geology v1Geology v1––3, 18303, 1830––3535) formalized concept.) formalized concept.

1.4 Uniformitarianism1.4 Uniformitarianism

The evidence seems to support the premiseThe evidence seems to support the premise

At left - an active Atlantic beach in South Carolina with ripple marks.

At right -fossilized ripples of a beach millions of years past based on age estimates from radiometric dating.

Fig 1.8 top Fig 1.8 bottom

1.4 Uniformitarianism1.4 UniformitarianismA modern earthquake mirrors events past that built A modern earthquake mirrors events past that built mountains like those in the distance.mountains like those in the distance.

Fig 1.9

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1.4 Uniformitarianism1.4 Uniformitarianism

Current perspectivesCurrent perspectives–– Not taken literallyNot taken literally

Early conditions likely differed (temperature, chemistry)Early conditions likely differed (temperature, chemistry)Conditions affect rates of processesConditions affect rates of processesEarly Earth processes likely occurred at different rates Early Earth processes likely occurred at different rates than today, although the same physical principles limited than today, although the same physical principles limited themthem……

–– Is Uniformitarianism predictive? Sort of Is Uniformitarianism predictive? Sort of ……Sure: in the future, mountains will wear down and oceans Sure: in the future, mountains will wear down and oceans will open and close cause they have before...will open and close cause they have before...However, it is less likely that we can predict where and However, it is less likely that we can predict where and when an earthquake will occur.when an earthquake will occur.

1.5 What is the Theory of Plate Tectonics?1.5 What is the Theory of Plate Tectonics?

A A ““newnew”” theory (c. 1960s)theory (c. 1960s)The solid lithosphere of Earth is composed of The solid lithosphere of Earth is composed of a number of plates. a number of plates. Over time these plates move (processes Over time these plates move (processes described later in book)described later in book)Some plates grow while others shrink, Some plates grow while others shrink, maintaining a balance of forces and area maintaining a balance of forces and area across Earthacross Earth’’s surface.s surface.


contain both continental

and oceanic crust

Some plates

Others are mainly oceanic crust

Fig 1.10


Divergent boundaryDivergent boundary–– New crustNew crust–– Crust becoming widerCrust becoming wider–– Shallow earthquakesShallow earthquakes–– Extrusive volcanismExtrusive volcanism–– MidMid--ocean ridge systemocean ridge system

Fig 1.11a


Convergent boundaryConvergent boundary–– Subducting zoneSubducting zone–– Plate is consumedPlate is consumed–– Deep earthquakesDeep earthquakes–– Volcanic chain aboveVolcanic chain above–– Ocean trenchesOcean trenches

Fig 1.11b


Transform boundaryTransform boundary–– Shearing zoneShearing zone–– Lots of earthquakesLots of earthquakes–– Little/no volcanismLittle/no volcanism–– E.g., California (San Andreas system)E.g., California (San Andreas system)

Fig 1.11c

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Hot spotsHot spots–– Fixed Fixed (sort of)(sort of) spot of spot of

rising mantle plumerising mantle plume–– Plate moves acrossPlate moves across–– Builds island chain in Builds island chain in

passingpassing

Fig 1.12

Measurements of plate motions using gps and other geodetic techniques supports the amount of uplift and movement through geologic time measured via radiometric age estimates for rocks.


The best evidence for plate tectonics is that it explains so many observations.

earthquakes

volcanoes

deep ocean trenches

Island chain from hot spots

Fig 1.10

The theory of plate tectonics = EarthThe theory of plate tectonics = Earth’’s s lithosphere is divided into a number of plates. lithosphere is divided into a number of plates. These plates move, either towards or away These plates move, either towards or away from one another, or past each otherfrom one another, or past each other……


The interaction of plates along their contact The interaction of plates along their contact boundaries accounts for the distribution of boundaries accounts for the distribution of earthquakes, volcanoes, and mountain beltsearthquakes, volcanoes, and mountain belts——and provides a basis for examining most Earth and provides a basis for examining most Earth processes and products.processes and products.

1.6 How does 1.6 How does …… work apply to Earth?work apply to Earth?

Earth is full of active processesEarth is full of active processes–– Water flowing in streamsWater flowing in streams–– Plate motionPlate motion–– MountainMountain--building building …… for examplefor example

These processes involve movement of Earth These processes involve movement of Earth materials.materials.Thus, by definition, Earth processes are forms Thus, by definition, Earth processes are forms of work.of work.

1.6 How does 1.6 How does …… work work apply to Earth?apply to Earth?

Work requires energyWork requires energyEnergy on Earth takes Energy on Earth takes various formsvarious forms–– StoredStored

PositionPositionForm (e.g., stress, Form (e.g., stress, petroleum)petroleum)

–– TransformedTransformedMotionMotionHeatHeat

Fig 1.13


Three modes of heat transfer

Only convection causes motion

Fig 1.14

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Sunlight heats the Sunlight heats the ground.ground.–– Causes air to riseCauses air to rise–– Cooler air replaces Cooler air replaces

the rising warm airthe rising warm air–– Convection occurs, Convection occurs,

transferring heat and transferring heat and moving mass.moving mass.

Fig 1.15b


Within EarthWithin Earth’’s crust s crust –– Cold dense rock sinks Cold dense rock sinks

in subduction zones. in subduction zones. Warmer, molten Warmer, molten matter inside rises matter inside rises and convection and convection occurs.occurs.

–– Again, transferring Again, transferring heat and moving heat and moving mass.mass.

Fig 1.15c

Potential energy of landscapesPotential energy of landscapes


ConvectionConvection--driven processes create driven processes create ““high spotshigh spots”” (mountains)(mountains)

Mountains are high relative to the rest of the landscape. This iMountains are high relative to the rest of the landscape. This is s potential energy.potential energy.

Water flowing down the mountain, or dislodged rocks or Water flowing down the mountain, or dislodged rocks or particles, realize this potential as motion.particles, realize this potential as motion.

This gradual flattening, erosion, is a powerful force explored This gradual flattening, erosion, is a powerful force explored (along with others) in Part IV.(along with others) in Part IV.

Movement of mass within and on EarthMovement of mass within and on Earth’’s surface is s surface is evidence of work.evidence of work.Work requires energy.Work requires energy.On Earth, sunlight and internal heat from radioactive On Earth, sunlight and internal heat from radioactive decay are the most prevalent sources of energy.decay are the most prevalent sources of energy.Heat is transferred by radiation, conduction, and Heat is transferred by radiation, conduction, and convectionconvection——the last of which is most important in the last of which is most important in Earth processes.Earth processes.Potential energy is a form of stored energy based on Potential energy is a form of stored energy based on physical position with respect to gravity. When mass physical position with respect to gravity. When mass falls, flows, or goes downhill, this energy is realized. falls, flows, or goes downhill, this energy is realized.


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Course description Geology lab - Centralia College ... Mount Hood volcano Tree buried by past lahar …and geology studies past history of the Earth Mount Rainier volcano, from the