Table Of Content

Earth Science CK-12Foundationisanon-profitorganizationwithamissiontoreducethecostoftextbook materialsfortheK-12marketbothintheU.S.andworldwide.Usinganopen-content, web-basedcollaborativemodeltermedthe"FlexBook,"CK-12intendstopioneerthe generationanddistributionofhighqualityeducationalcontentthatwillservebothas coretextaswellasprovideanadaptiveenvironmentforlearning. www.ck12.org CK-12usersshouldtreatthisFlexBookasanonlinetextbook.ThisFlexBookunderwent athoroughreviewconductedbypracticingteachers,domainexperts,copyeditors,and technicaleditors.Itcanbeusedinitscurrentform,"flexed"(customized),and/orprinted bytheuser.CK-12supportsfeedbackonallofitsFlexBookssothattheycanbecontinually improvedandupdated,whileremainingalignedwithstatestandardsandcurriculum guidelines. ThisFlexBookcontainsreferencestoadditionalresourcesandlinkstoexternalwebsites thatareprovidedbythecontributingauthorsassupplementalmaterials.CK-12Foundation neitherendorsesthesereferencesnorisresponsiblefortheircontentoravailability.Also, theinclusionofanyreferencetoanexternalresourceorlinktoawebsitedoesnotimply endorsementbyCK-12Foundationoftheirowners,productsorservices. ThismaterialislicensedundertheCreativeCommonsAttribution-ShareAlikelicense (http://creativecommons.org/licenses/by-sa/3.0/). Printdate:2009-06-1116:15 CK12psn:810cf1364629725c50fe6b6c59b162d2 ii Authors CraigFreudenrich,JohnBenner,DavidBethel,DanaDesonie, CorlissKarasov,MaryLusk,ErikOng,KurtRosenkrantz,and Julie Sandeen. Supported by CK-12 Foundation iii iv Contents 1. WhatisEarthScience?.................................................................................................................... 1 2. StudyingEarth’sSurface............................................................................................................... 19 3. Earth'sMinerals.............................................................................................................................. 55 4. Rocks............................................................................................................................................... 85 5. Earth's Energy.............................................................................................................................. 109 6. Plate Tectonics............................................................................................................................. 127 7. Earthquakes.................................................................................................................................. 159 8. Volcanoes...................................................................................................................................... 207 9. WeatheringandFormationofSoil.............................................................................................. 235 10. Erosion and Deposition............................................................................................................... 251 11. Evidence About Earth's Past...................................................................................................... 293 12. Earth's History.............................................................................................................................. 319 13. Earth'sFreshWater...................................................................................................................... 337 14. Earth's Oceans............................................................................................................................. 359 15. Earth's Atmosphere..................................................................................................................... 393 16. Weather......................................................................................................................................... 431 17. Climate.......................................................................................................................................... 479 18. Ecosystems and Human Populations........................................................................................ 517 19. HumanActionsandtheLand...................................................................................................... 545 20. HumanActionsandEarth'sResources..................................................................................... 559 21. HumanActionsandEarth'sWaters............................................................................................ 573 22. Human Actions and the Atmosphere......................................................................................... 599 23. ObservingandExploringSpace................................................................................................. 621 24. Earth, Moon, and Sun.................................................................................................................. 655 25. The Solar System......................................................................................................................... 681 26. Stars, Galaxies, and the Universe.............................................................................................. 719 v vi 1. What is Earth Science? Nature of Science LessonObjectives • Explaintheimportanceofaskingquestions. • Statethestepsofthescientificmethod. • Describethethreemajortypesofscientificmodels. • Useappropriatesafetyprecautionsinsideandoutsidethesciencelaboratory. Introduction Thinkofyourfavoritesciencefictionmovie.Whatisitabout?Maybeit’saboutspaceshipsgoingtodistant planets, or people being cloned in laboratories, or undersea civilizations, or robots that walk among us. Theseentertainingimaginingsaremake-believefantasies,that’swhythey’recalledscience“fiction.”They arenotreal.Butwhyaretheycalled“science”fiction? The answer is that science uses a disciplined process to answer questions. In science, “disciplined” does notmeanwell-behaved.Itmeansfollowingorderlystepsinordertocomeupwiththebestanswers.Science involvesobserving,wondering,categorizing,communicating,calculating,analyzing,andmuchmore.Inorder toconvertcreativityintoreality,weneedscience.Inordertotravelbeyondwhereanyonehasgonebefore, weneedscience.Inordertounderstandtheworld,makesenseofit,andconserveit,weneedscience.In ordertoconfirmourbestguessesabouttheuniverseandthethingsinit,weneedscience.Sciencefiction storiesextendandexpandonalltheideasofscienceandtechnologyincreativeways. AskingQuestions Whyistheskyblue? Howtallwillthistreegrow? Whydoesthewindblowsohard? Willitbecoldtonight? Howmanystarsareoutthere? ArethereplanetslikeEarththatorbitaboutsomeofthosestars? Howdidthisrockgetholesinit? Whyaresomerockssharpandjagged,whileothersareround? Youprobablyaskyourselfathousandquestionsaday,manyofwhichyouneveraskanyoneelse.Formany ofthequestionsyoudoask,youneverevengetananswer.Butyourbrainkeepschurningwithquestions andcuriosity.Wecan’thelpbutwanttoknow. Thelistofquestionsabovearesomeofthesamequestionsthatscientistsask.Sciencehasdevelopedover centuries and centuries, and our ability to measure the tiniest trait has increased immensely. So although there is no wrong question, there are questions that lend themselves more to the scientific process than 1 others.Inotherwords,somequestionscanbeinvestigatedusingthescientificmethodwhileothersrelyon purefaithoropinion. ScientificMethods Thescientificmethodisnotalistofinstructionsbutaseriesofstepsthathelptoinvestigateaquestion.By usingthescientificmethod,wecanhavegreaterconfidenceinhowweevaluatethatquestion.Sometimes, theorderofthestepsinthescientificmethodcanchange,becausemorequestionsarisefromobservations ordatathatwecollect.Figure1illustratesthebasicsequencefollowedinthescientificmethod. Figure1:TheScientificMethod. (Source:Createdby:ErikOng,License:CC-BY-SA) Question Thescientificmethodalmostalwaysbeginswithaquestionthathelpstofocustheinvestigation.Whatare we studying? What do we want to know? What is the problem we want to solve? The best questions for scientificinvestigationarespecificasopposedtogeneral,theyimplywhatfactorsmaybeobservedorma- nipulated. Example:Afarmerhasheardofafarmingmethodcalled“no-tillfarming.”Inthismethod,certaintechniques in planting and fertilizing eliminate the need for tilling (or plowing) the land. Will no-till farming reduce the erosionofthefarmland? 2 Figure2:SoilErosion. (Source:http://en.wikipedia.org/wiki/Soil_erosion,License:GNU-FDL) Research Beforewegoanyfurther,itisimportanttofindoutwhatisalreadyknownaboutthetopic.Youcanresearch a topic by looking up books and magazines in the library, searching on the Internet, and even talking to peoplewhoareexpertsinthearea.Bylearningaboutyourtopic,you’llbeabletomakethoughtfulpredictions. Your experimental design might be influenced by what you have researched. Or you might even find that your question has been researched thoroughly. Although repeating experiments is valid and important in science, you may choose to introduce new ideas into your investigation, or you may change your initial question. Example:Thefarmerdecidestoresearchthetopicofno-tillfarming.ShefindssourcesontheInternet,at thelibrary,andatthelocalfarmingsupplystorethatdiscusswhattypeoffertilizermightbeusedandwhat thebestspacingforhercropwouldbe.Sheevenfindsoutthatno-tillfarmingcanbeawaytoreducecarbon dioxideemissionsintotheatmosphere,whichhelpsinthefightagainstglobalwarming. Figure3:Thefarmerwouldneedtoresearchno-tillfarmingmethods. (Source: http://upload.wikimedia.org/wikipedia/commons/a/a8/No_till_farming_SemisDirect_USDA.jpg, Li- cense:GNU-FDL) 3 Hypothesis Nowthatyouhaveresearchedthetopic,youcanmakeaneducatedguessorexplanationtothequestion. Thisisyourhypothesis.Thebesthypothesisisdirectlyrelatedtothequestionandistestable,sothatyou candoexperimentstomeasurewhetheryourhypothesisiscorrect. Example:Thefarmerhasresearchedherquestionanddevelopedthefollowinghypothesis: No-tillfarmingwilldecreasethesoillossonhillsofsimilarsteepnessascomparedtothetraditionalfarming techniquebecausetherewillbelessdisturbancetothesoil. Experiment Notallquestionscanbetestedbyexperimentation.However,manyquestionspresentuswithwaystotest them thatgive us the clearest conclusions.When we design experiments,we select the factorthatwill be manipulatedorchanged.Thisistheindependentvariable.Wewillalsochooseallofthefactorsthatmust remainthesame.Thesearetheexperimentalcontrols.Finally,wewillchoosethefactorthatwearemea- suring,aswechangetheindependentvariable.Thisisthedependentvariable.Wemightsaythatthede- pendentvariable“depends”ontheindependentvariable.Howmuchsoiliserodeddependsonthetypeof farmingtechniquethatwechoose. Figure4:Afarmertakescarefulmeasurementsinthefield. (Source:http://en.wikipedia.org/wiki/Agricultural_science,License:GNU-FDL) Example:Thefarmerwillconductanexperimentontwoseparatehillswithsimilarslopes(orsteepnesses). Ononehillshewilluseatraditionalfarmingtechniquewhichincludesplowingtostirupthenutrientsinthe soil.Ontheotherhill,shewilluseano-tilltechniquebyspacingplantsfurtherapartandusingspecialized equipmentthatplantstheplantswithouttilling.Shewillgivebothsetsofplantsidenticalamountsofwater andfertilizer. Inthiscase,theindependentvariableisthefarmingtechnique—eithertraditionalorno-till—becausethatis whatisbeingmanipulated.Inordertobeabletocomparethetwohills,theymusthavethesameslopeand thesameamountoffertilizerandwater.Ifonehadadifferentslope,thenitcouldbetheanglethataffects theerosion,notthefarmingtechnique,forexample.Thesearethecontrols.Finally,thedependentvariable is the amount of erosion because the farmer will measure the erosion to analyze its relatedness to the farmingtechnique. DataandConclusion During the experiment, we may make many measurements. These measurements are our observations thatwillbecarefullyrecordedinanorganizedmanner.Thisdatastaysorganizedinchartsortablesthatare clearlylabeled,sothatwewon’tforgetwhateachnumberrepresents.“Data”referstothelistofmeasurements that we have collected. We may make written descriptions of our observations but often, the most useful data is numerical. For example, length is measured in centimeters, meters, or kilometers. Temperature is measuredindegreesCelsius.Evendatathatisdifficulttomeasurewithanumberissometimesrepresented 4