charles darwin was a geologist - university of …k charles darwin was a geologist · 13 the icon of...

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o n e · CharlesDarwinWasaGeologistInorganic Complexity and the Rock Record

jill s. schneiderman

TheEarth’sfossilrecordrecordsthechangesinlifeonthisplanetovertime;simi-larly,theEarth’srockrecordpreservescomplexstructuresthatrecordthechangesinrocksandmineralsovertime.Consequently,alltheaspectsoflivingthingsthattroubleintelligentdesigncreationists—theircomplexityandwhatseemtobetheabundanttracesoflongandcontingentevolutionarychange—alsoapplytoalltheEarth’smaterials,whetheroncelivingornot.Therefore,onecouldalsoask,ifasupernaturalpowerdesignedlivingthings,whataboutnonlivingthings?DidtheEarth’sinterior,crust,andsurfaceevolvenaturally,accordingtothemateriallawsofphysicsandchemistry,orwerethey“intelligentlydesigned”aswell?Ifnotsodesigned,whynot?Howdoweknowwhethertheywereorweren’t?Intelligentdesign (ID) creationists currently ask these seemingly hypothetical questions.Thoughgeologicalphenomenarequirenaturalistic/materialistichistoricalexpla-nations, intelligent design creationists offer inadequate, ahistorical ones. In thisessay,Iusebothlarge-scaleandsmall-scalegeologicfeaturestodemonstratethestrength of historical explanations to understand extraordinarily complexgeologicstructures.

In The Design Revolution: Answering the Toughest Questions about Intelligent Design, intelligent design creationist William Dembski writes, “As a theory ofbiologicaloriginsanddevelopment,intelligentdesign’scentralclaimisthatonlyintelligentcausesadequatelyexplainthecomplex, information-richstructuresofbiologyandthatthesecausesareempiricallydetectable”(Dembski2004,p.34).

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However,Dembskialsobroadensthepurviewofintelligentdesignandstatesthat“intelligentdesignis thesciencethatstudiessignsof intelligence”(p.10).So, itcomesasnosurprisetothisgeologistthatDembskiopenschapter1ofhisbookonintelligentdesignwithastatementnotaboutorganismsbutaboutrocks:“ThinkofMountRushmore—whataboutthisrockformationconvincesusthatitwasduetoadesigningintelligenceandnotmerelytowindanderosion?”Inthisregard,he is not unlike the sixteenth-century astrologer/astronomer Johannes Kepler,who postulated that craters on the moon were intelligently designed by moondwellers.Similarly,intelligentdesigncreationistslaudpublicationofCarlFroede’sGeology by Design: Interpreting Rocks and Their Catastrophic Record (2007)asan“importantreferencetextforhome-schoolers”thatasks“whatoftherocksbeneathourfeet?”(Goddard2007).

Intelligent design creationists believe that, in their words, life is irreduciblycomplex,andthereforecouldnothaveevolvedonitsown.Thus,acreatormusthavedesignedlifeonourplanet.Thoughfocusingexplicitlyonlife,thetraditionalpurview of biologists, this assertion of intelligent design creationists extends toinorganicEarthmaterials andconstitutes an indictmentnotonlyofbiologybutgeology.ItthereforedemandsparticularlygeologicalresponsessuchastheoneIofferinthisessay.

Overmanydecades,creationistshavebattledwithandfeltthreatenedbygeolo-gists. The arena of contention has been time. Many first-generation creationistsinsisted that theEarth isnotnearlyasoldaswegeologistswouldhave it.Thiscampofyoung-Earthcreationistsstillpersists,althoughthenumbersofcampershavedeclined.Forgeologicalprocesses tooperateas theyclearlydo, theEarthsimply must be very old. Abundant evidence based on years of geoscientificinquiry,investigation,andpeerreviewrevealsthattheEarthisapproximately4.5billionyearsold.Inthefaceofthisevidence,someyoung-Earthcreationistshavemorphed into old-Earth creationists, who accept the ancient age of the Earth.Thesebelievershaveabandoned timeas thearenaofcontroversy. Instead,old-Earthcreationistsinsistthatlifeobservedtodayaslivingcreaturesandasfossilsentombedinrocksistoocomplextohavedevelopedonitsownovertime;itmusthavebeendesignedbyacreator.Manyoftheseold-Earthcreationiststodaybasetheirargumentsoncomplexity.

Althoughthebulkof intelligentdesigncreationistsareold-Earthcreationists,whoallowampletimeinEarth’shistoryforgeologicalprocessestooperate,theirinsistencethataspectsofthenaturalworldaretoocomplextohavedevelopedontheirownconstitutesanindictmentofgeology.Forexample,intheGrandCanyon,

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c h a r l e s d a r w i n w a s a g e o l o g i s t · 13

theiconofgeologicalthought,inwhichEarthscientistsinterpretoneofthesim-plest geologic histories in the United States, intelligent design creationists seeevidenceofacreator(Wilgoren2005).FarmorecomplexgeologiesthanthatoftheGrandCanyonhavebeenstudiedandexplainedscientificallybyEarthscien-tists.Yetintelligentdesigncreationistsresorttofaithtounderstandthisgeologicfeaturethat,althoughstunning,isas“simpleascake”—sosimplethatgeoscientistsandEarthscienceteachersalikerefertoitas“layercakegeology.”ThatintelligentdesigncreationistsseeintherocksoftheGrandCanyonwhattheyconsidertobelegitimateevidenceofacreatorsuggeststhatwegeologistsreallydon’tknowwhatwearetalkingaboutwhenitcomestoexplainingphysicallandscapes,structures,andphenomena.Butnaturalistic/materialisticreasoningsufficestoexplainexceed-inglycomplexgeologicalfeaturesandphenomenaaswellassimpleoneslikethoseoftheGrandCanyon.Oneneednotemployclaimsabouttheactionsofanintel-ligentcreatortoexplainsuchphysicalcomplexity.

Geologists’ explanations of complex structures are based on observations soobviousandroutinethatgeoscientistsrefertothemaslaws:thelawofstratigraphicsuperposition (in an undisturbed sequence of strata, the oldest strata lie at thebottomandnecessarilyhigherstrataareprogressivelyyounger);thelawoforigi-nalhorizontality(almostallstrataareinitiallynearlyhorizontalwhentheyform);the law of original lateral continuity (strata have continuous tabular shapes,“pinchingout”laterallytoathicknessnearzeroorabuttingagainst thewallsofthe natural basin in which they formed); the law of cross-cutting relationships(faultsandinvadingigneousrocksarealwaysyoungerthanthefaultsorrocksthatthey transector intrude); andfinally, the lawof components (abodyof rock isyoungerthananotherbodyofrockfromwhichanyofitscomponentsarederived).Our understanding is bolstered by the principles of uniformity of law (the ideathatnaturallawsdonotchangeovertime)andtheuniformityofprocess(theideathatthepresentisthekeytothepast).DespitethefactthattheselawscanguideanycarefulobservertoprovidenaturalisticexplanationsformanyofEarth’spro-cesses and the features that arise from them, intelligentdesigncreationistshavesoughttodevelopsupernaturalexplanations—thoseoutsidetherealmofscience—forvariousfeaturesoftheEarth.

Forexample,thoughplatetectonictheory,oneofgeology’sgreatestcontribu-tions to twentieth-centuryscience, thoroughlyexplains thegeomorphic featuresofcontinentsandoceansaroundtheglobe,creationistshavedevelopedamodeltermed“catastrophicplatetectonics,”whichallowsacompressedtimescaleanddeploysgeologicalprocessestoprovideamechanismforthebiblicalflood(Austin

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et al. 1994). As a means of finding a source of biblical floodwater, creationistarticulations about catastrophic plate tectonics misappropriate numerous well-understoodconceptswithingeology, includingmantleconvection(thecreepingmotionoftheEarth’srockymantleinresponsetounstablevariationsinitsdensity),geomagnetic reversals (changes in the orientation of Earth’s magnetic field),and geochemical processes such as evaporation and precipitation(Baumgardner2003).

ToshowhowonemightbetemptedtoinvokeanintelligentcreatortoexplaintheexistenceofcomplexfeaturesoftheEarthatboththemacroscopicandmicro-scopicscales,IreproduceandinterpretimagesofsomecomplexEarthstructures.Atfirst look,eachoftheseimagespresentsanendproductthatrequiresaseriesofevents thatmightseemimpossiblewithoutthe interventionofacreator.Yet,eachsetoffeatureshasawell-documentedhistoryconfirmedinthecourseofthenormalscientificresearchthatcharacterizesthefieldofEarthscience.

GEOLOGICALSECTIONS

Geologicalsectionsorcross-sectionsshowthepatternsofrocksasexposedonthesideofaroadcutoronthewallofatrench.Wheninterpretedcarefully,theyrevealthehistoriesofsequencesofrocksatornearthesurfaceoftheEarth;thatis,onecan infer the order of events that produced the section. In fact the essence ofgeology, going back to the eighteenth-century Scottish Enlightenment and thedaysofJamesHutton,ourscience’s“founder,”istoobserverocks“inthefield”andallowthemto“telltheirstories.”Tointerprettheorderofeventsinageologi-calsectionusingthelawsofsuperposition,originalhorizontality,lateralcontinu-ity,cross-cuttingrelationships,andcomponentsisto“read”thenaturalhistoryofthatportionoftheEarth.

The complex section in figure 1.1 shows a view across New York’s HudsonRiverinthevicinityoftheGeorgeWashingtonBridge.Ingeologicalparlance,itshowswestwardtiltedstrataoftheNewarkBasinandthePalisadessillwiththeirnonconformable relationship to folded metamorphic rocks of New York City(Berkey1948).

How could this complex series of contorted, tilted, and gouged rocks haveformed?Anintelligentdesigncreationistmightwellsummonthemightyhandsofa creator tohaveupended some rockswhilehaving squeezedandconsequentlybentthehardestamongthem,thegneissandschist,withonehandwhileusingthefingersoftheotherhandtogougeachannelalongwhichtheHudsonRivernow

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flows.Buttocapitulatetosuchanexplanationinthenameof“irreduciblecomplex-ity”woulddeny theobserver theopportunity tounderstand thenaturalmecha-nismsthatovertimewouldindeedhaveproducedthissectionoftheEarth.

Features of the Fordham gneiss, Inwood limestone (marble) and Manhattanschistformations,togetherdenotedonthefigureasthefloorofancientcrystallinerocks,indicatethattheyoriginatedasancientbedrocktoppedbyablanketofsedi-mentary and volcanic rocks as many as 550 million years ago on the edge of aNorthAmericancontinentrimmedwithvolcanoes.Theancientgeographyofthistime inEarthhistorywasakinto today’sJapanesevolcanic islandsrimmingthecoast of China. During a protracted episode of mountain building, known togeologistsasanorogeny,thebedrockandvolcanicandsedimentaryrockswerefoldedandmetamorphosedinacollisionthatultimatelyproducedtheAppalachianMountainchain.

Experimental and field-based studies indicate that when rocks encounter achangeinpressureandtemperatureasoccursinazoneofcollision,theyfracture,bend,andgenerallyreorganizethemselvessothatthemineralgrainsthatoriginallyformed them change their chemical compositions and physical structures. Thustheoriginalrocksmetamorphose—changetheirform—intorockswithnewmin-eralsandtexturesthatonlybarelyresembletheprotoliths.Indeedthisisacreationstory, but it is a geological one; the rocks tell their own origin story, one that

figure1.1.Cross-sectionacrosstheHudsonRiverbetweenNewYorkandNewJersey(Berkey1948).

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dependsonlyonnaturalprocesses,andwecometounderstandhowtheFordham,Inwood,andManhattanformationsarose.

NointelligentdesigncreationistshavethusfardirectlychallengedtheveracityofthisaccountoftheformationofthebasementrocksinsoutheasternNewYorkState.However,theirmodelof“catastrophicplatetectonics”indirectlycondemnssuch an account. Catastrophic plate tectonics requires “runaway subduction” inwhich slabs of oceanic crust break off from the Earth’s lithosphere and quicklysink deep into the Earth’s mantle (Austin et al. 1994). Such rapid tectonics isincompatiblewiththepaceofmetamorphismsincetherecrystallizationanddefor-mationnecessaryfortheformationofmetamorphicrocksisaslowprocess.Weknowthisbecause,forexample,thoughdiamondandgraphitearebothmineralsmade up wholly of carbon, diamond rings do not transform into graphite inanyone’s lifetime; ingeologicalparlance, theypersistmetastably.Thus itcomesasnosurprisethatintelligentdesigncreationistsassertthat“theinitialstatefromwhichtherunawayemergedwasbuiltintotheEarthasGodoriginallyformedit”(Baumgardner2003,p.12).Nevertheless,wecanexplainthecomplexityreflectedin the basement rocks of southeastern New York State using only the lawsofnature.

The“greatunconformity”abovethecrystallinebasementrocksshowninfigure1.1propelsanobserverforwardintimeintothe“Newarkseriesofsandstonesandshales”and the“Palisades trap ridge.”Basedon its contained fossils, aswell asgrainsizesandcompositions,weknowthatthispackageofrocksisathicksequenceofmiddle-aged(Mesozoic)sedimentarystrataandvolcaniclayers.Usingthelawsoforiginalhorizontality,lateralcontinuity,superposition,cross-cuttingrelations,andcomponents,aswellastheprinciplesofuniformityoflawanduniformityofprocess,geologistshavebeenabletodiscernthattheNewarksedimentarystrataweredepositedinabasinintowhichseawaterneverflowed.Theybecameinter-layeredwithigneousrocksthatintrudedintoanderuptedonthesedimentaryrocksinprocessesnotunlike those thatoccur today in theriftzonesofeasternAfrica(MerguerianandSanders1994).ThissequenceoflayersformedinassociationwiththeopeningoftheAtlanticOcean(Olsen1980).Faults,planesalongwhichrockshavemovedagainstoneanother,intheareaindicatethathugestressesassociatedwith the breakup in the early Mesozoic of a large “supercontinent”—known togeologists as Pangaea—produced a series of basins into which sediments wereerodedfromadjacenthighareas.Therustedredcolorofsomeofthesedimentarylayers indicates to geologists that, much as metal rusts when exposed to airandwater, iron in the sediments interactedwith oxygen. Thus, the basins were

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periodicallyexposed toairwhennotcovered in shallowwater. Inmanyplaces,“fossilraindrops”preservearecordofrainshowersfallingonmoistmuds(Passow2007).Theuniformitiesoflawandprocessprovideampleevidenceforthebasins’origininerosioncausedbyprecipitation.Evidencefromfossilscorroboratesthisinterpretation:wormsorotherburrowingorganismslefttracks,asdidsomeoftheearliest dinosaurs as well as other large extinct reptiles such as Clepysaurus (Rutiodon)(2007).Abovetheserockunitsrestthe“riversiltandbouldersfillingtheancientHudsonRivergorge,”carvedthroughtheworkofwaterandiceintherelatively recent geological past (Merguerian and Sanders 1990). Thus, it is byreadingtherecordoftherocksthatEarthstructuresofenormouscomplexityareexplainedwiththeaidofnaturallaws.

PINWHEELGARNETSAND MINERALINCLUSIONS

Photomicrographsofrocksamplesarephotographsofpolished,verythinslicesof rock taken through a microscope. They frequently reveal that the internalstructuresofrocksaremorecomplexthanisevidenttothenakedeye.Examinedthrough the microscope, such thin sections are kaleidoscopically beautifuland resemble stained-glass windows. Mineralogists and petrologists (geologistswhostudythehistoryoftheEarthbyexaminingthechemicalandphysicalmicro-structures of rocks in thin section) determine the histories of rock units bydetailing thesemicrostructuresandtheoftenmultiplegenerationsofevents thattheyconcludemusthaveoccurredtoproducethem.

Theimageshowninfigure1.2,whoselongdimensiondoesnotexceedthirteenmillimeters,displaysagarnetgrainwithspiral-shapedinclusiontrails(smallpiecesofoneormoretypesofmineralsenclosed inahostmineral) inarockfromtheAppalachian mountain range in Vermont. Such garnets have been described asamongthemostalluringandperplexingmicrostructuresindeformedmetamorphicrocks;theylookliketheyhaverolledlikesnowballsinthedirt(Moore1999).Howwere they formed? In the face of such tremendous complexity one might betemptedtoinvokeanartisticanddexterouscreator.However,geologistsareableto use the law of cross-cutting relationships and the law of components on themicroscopic scale for textural analysis, that is, to determine in what order themineralsformed,aswellastheirknowledgeofchemicaldiffusion,themovementofelementsfromonepartofasolidtoanother,tooutlinetheremarkablehistoryoftherocksthatcontainthem.

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Thegarnetgrain in this imagecontainscurvedtrailsof inclusions—incorpo-ratedbitsofother typesofmineralssuchasquartzand ilmenite—that look likepreexistingberriesincludedinpancakes.Theoriginoftheseinclusionshasbeenthesubjectofdebateamongmetamorphicpetrologists.Someinvestigatorsbelievethat the mineral inclusion trails indicate that such garnet grains rotated as theygrew, while others suggest that the enclosing grains rotated around the garnetcrystals.Thedistinctionisnotcriticalbecauseundereitherinterpretationthepat-ternsofinclusionssuggestthatthegarnetgrainswerenotcreatedasweseethem;theyhaveahistory,andclearlygrewas therockswereactivelydeformed(Bell1985;BellandJohnson1989;Rosenfeld1970;Rosenfeld1987;Schoneveld1977).

Suchcurvedinclusiontrailsareacommonfeatureoflargecrystals,knownasporphyroblasts,inrocksfromdeformedmetamorphicregions.Theyhavebeenasourceofintrigueforalmostacenturyand,althoughcomplex,havethepotentialtoaidunderstandingaboutmetamorphicandstructuralprocessesthatoccurduringthe formation of mountains. Metamorphic petrologists and structural geologistsstrive to understand the metamorphic and deformation history that a rock hasexperienced. One problem that such geologists encounter is limited access to

figure1.2.Garnetgrainwithspiral-shapedinclusiontrails,fromtheAppalachianmountains,Vermont(Moore1999).

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informationaboutthishistory.Todeterminetheearlyhistoryofadeformedrock,metamorphicpetrologistsandstructuralgeologistsmustfind“windows”asawaytolookintothepast.

Whatoftherocksbeneathourfeet?Theyaretheresultofphysicalprocessesthatfollownaturallaws.Asthefossilrecordservesasawindowforpaleontolo-gists,inclusion-riddledporphyroblastsserveaswindowsformetamorphicpetrolo-gists and structural geologists as they enumerate the sequential development ofmetamorphicmineralstocomprehendepisodesofmountainbuildingintheEarth’shistory (Johnson1999).Similarly,geologic cross-sections serveaswindows forstratigraphers and sedimentologists as they articulate the cycles of deposition,erosion,andupliftrecordedinremnantsofrock.

REFERENCES

Austin, S.A. 1994. Grand Canyon: Monument to Catastrophe. Institute for CreationResearch,ElCajon,CA.

Austin,S.A.,J.R.Baumgardner,D.R.Humphreys,A.A.Snelling,L.Vardiman,andK.P. Wise. 1994. Catastrophic Plate Tectonics: A Global Flood Model of EarthHistory.Pp.609–21inR.E.Walsh,ed.,Proceedings of the Third International Con-ference on Creationism.CreationScienceFellowship,Pittsburgh,PA.

Baumgardner, J.R. 2003. Catastrophic Plate Tectonics: The Physics behind theGenesisFlood.Pp.113–26inR.L.Ivey,Jr.,ed.,Proceedings of the Fifth International Conference on Creationism.CreationScienceFellowship,Pittsburgh,PA.

Bell,T.H.1985.DeformationPartitioningandPorphyroblastRotationinMetamor-phicRocks:ARadicalRe-Interpretation.J. Metamorph. Geol.3:109–18.

Bell, T.H., and S.E. Johnson. 1989. Porphyroblast Inclusion Trails: The Key toOrogenesis.J. Metamorph. Geol.7:279–310.

Berkey, C.P. 1948. Engineering Geology in and around New York. Pp. 51–66 inAgnesCreagh,ed.,Guidebook of Excursions.GeologicalSocietyofAmerica,sixty-firstannualmeeting,NewYork.

Dembski,W.A.2004.The Design Revolution: Answering the Toughest Questions about Intelligent Design.InterVarsity,DownersGrove,IL.

Goddard, J. 2007. Geology by Design, November 16. www.shelleytherepublican/category/education/science/junk-science.

Humphreys,D.R.1990.PhysicalMechanism forReversalsof theEarth’sMagneticFieldduringtheFlood.Pp.130–37inR.E.WalshandC.L.Brooks,eds.,Proceed-ings of the Second International Conference on Creationism,vol.2.CreationScienceFellowship,Pittsburgh,PA.

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Johnson,S.E.1999.PorphyroblastMicrostructures:AReviewofCurrentandFutureTrends.American Mineralogist84:1711–26.

Merguerian, C. 2002. Hofstra University Field Guidebook: A GeologicalTransect from New York City to New Jersey. www.dukelabs.com/Abstracts%20and%20Papers/1CManual0209.htm.

Merguerian,C.,andJ.E.Sanders.1990.Trip 14: Geology and History of the Hudson River Valley, 28 October 1990.NewYorkAcademyofSciencesSectionofGeologi-calSciencesTripsontheRocksGuidebook,NewYork.

———.1994.Post-NewarkFoldsand-Faults:ImplicationsfortheGeologicHistoryoftheNewarkBasin.Pp.57–64inG.N.Hanson,ed.,Geology of Long Island and Metropolitan New York, 23 April 1994.StateUniversityofNewYorkatStonyBrook,LongIslandGeologists,ProgramwithAbstracts,StonyBrook,NY.

Moore, R. 1999. Doubly-Curved, Non-cylindrical Surface. wwwtexdev.ics.mq.edu.au/GeoMath/scans/.

Olsen,P.E.1980.TriassicandJurassicFormationsoftheNewarkBasin.Pp.2–40inW.Manspeizer,ed.,Field Studies of New Jersey Geology and Guides to Field Trips.New York State Geological Association, fifty-second annual meeting, RutgersUniversity,Newark,NJ.

Passow, M.J. 1999–2006. Wandering the Watersheds: Hackensack Meadow-lands.Earth to Class.LamontDohertyEarthObservatory,ColumbiaUniversity.www.Earth2class.org/virtualtour/hackensack/hackensack.php.

Rosenfeld,J.L.1970.RotatedGarnetsinMetamorphicRocks.Geol. Soc. Am., Spec. Pap.129:105.

———.1987.RotatedGarnets.Pp.702–8inC.K.Seyfer,ed.,Encyclopedia of Struc-tural Geology and Plate Tectonics.VanNostrandReinhold,NewYork.

Schoneveld,C.1977.AStudyofSomeTypicalInclusionPatternsinStronglyParac-rystallineRotatedGarnets.Tectonophysics39:453–71.

Wilgoren,J.2005.SeeingCreationandEvolutioninGrandCanyon.New York Times,October6.

Wise,K.P.2002.Faith, Form, and Time: What the Bible Teaches and Science Confirms about Creation and the Age of the Universe.BroadmanandHolman,Nashville,TN.

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