GEOSCIE CE REPORTSFALL 1998

No. 26

HISTORICAL BIOGEOGRAPHY OFSOUTH AMERICA, PART II:

FOSSIL VERTEBRATES

Jim Gibson, Geoscience Research Institute

Introduction

This section focuses on SouthAmerican fossil vertebrates, ex­cluding marine fish. Extinct familieswill be emphasized here, as livingfamilies were considered in Part I.For convenience, the fossil record ofSouth American families will bedivided into three portions: Paleozoicand Mesozoic; Paleogene; and Neo­gene (see Figure I). Terrestrial andaquatic families are consideredseparately. Flying vertebrates are not

SYSTEM SERIES

ERA OR PERIOD OR EPOCH

Quaternary Holocene(Recent)Pleistocene

Cenozoic Neogene PlioceneMioceneTertiary

OligocenePaleogene Eocene

Paleocene

Cretaceous Upper, LowerMesozoic Jurassic Upper, Middle, Lower

Triassic Upper, Middle, Lower

PermianCarboniferous

Pennsylvanian Upper, Middle, LowerPaleozoic Mississippian Upper, Lower

Devonian Upper, Middle, LowerSilurian Upper, Middle, LowerOrdovician Upper, Middle, LowerCambrian Upper, Middle, Lower

Precambrian Upper, Middle, Lower

Figure 1. The geologic column is themaster sequence or rock layers whereverthey are found.

included. Data for fossil distributionswere taken mostly from Carroll (1988)and Benton (1993).

Biogeographic Relationships ofSouth American Fossil TerrestrialVertebrates

1. Aquatic families

Twenty-two extinct families ofaquatic vertebrates (excluding marinefish) are known as fossils from SouthAmerica (see Figure 2). Twelvefamilies probably lived in fresh water,including two families ofgiant amphi­bians, nine families of reptiles (seeFigure 3), and one of birds. Most ofthe reptiles are crocodile-like inappearance. Eleven families arerestricted to strata below the Neogene.Five of these are widespread, two areendemic to South America, three areshared only with northern continents(one reptilian and one bird family), andone (an amphibian family) is restrictedto South America and Australia. TheNeogene family is a crocodilian familyrestricted to South America.

Another ten extinct familiesprobably lived in the sea. These in­clude six families of reptiles, one ofbirds, and three families of whales.The whale families are restricted to the

Extinct Aquatic Families

Northern

Figure 2. Most of South America's ex­tinct families ofaquatic vertebrates areshared with the northern continents, butnot the other southern continents.

Neogene, while the other families arerestricted to sediments below theNeogene. One family, the Meso­sauridae, is found only in Permiansediments of South America andAfrica (see Figure 2). Four of theMesozoic families and one family ofwhales are shared only with thenorthern continents. The remainingfour families are widespread.

Most living families of SouthAmerican marine mammals andfreshwater fishes are restricted toNeogene sediments, but some arefound in sediments lower in thegeologic column. Three aquaticfamilies now living in South Americahave Mesozoic fossils in SouthAmerica. They include frogs, fresh-

the southern continents, and one (aturtle) is widespread. There are morenorthern links than southern amongSouth American aquatic vertebratefamilies, though the importance of thesouthern links is often emphasized.

2. Paleozoic and Mesozoicterrestrial families

Fifty families of terrestrialvertebrates are found as fossils in thePaleozoic and Mesozoic sediments ofSouth America. Only two are livingin South America today - theiguanas and the opossums. Bothfamilies have widespread fossildistributions in Cenozoic sediments.The remaining 48 families are extinct(see Figure 4).

The extinct groups include tenfamilies of mammals, eight of the­rapsid reptiles, and thirteen of dino­saurs. The mammals are all restrictedto the Cretaceous of South America,except one family which extends into

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water fish, and turtles. One of theseis endemic to South America, asecond is restricted to the southerncontinents, and one has a widespreadfossil record. Another five livingfamilies have Paleogene fossilappearances in South America. Theseinclude fish, frogs, turtles, and onefamily of birds. One family is wide­spread, two are endemic, one isnorthern and one is southern.

None of the aquatic families needhave been in the ark, and the distri­butions of their fossils are here con­sidered to be primarily the result offlood processes. .

It is interesting to compare thenumber of biogeographic links withthe northern continents and with thesouthern continents. For extinctaquatic groups with Mesozoic fossils,there are two southern links and sevennorthern links. For living familieswith Mesozoic fossils, one (a fish) isendemic, one (a frog) is restricted to

Figure 3. Mesosaurs areextinct reptiles foundonly in Permian sedi­ments of South AmericaandAfrica. Photo by JimGibson.

Figure 5. Kannemeyeri­idae is a family of ther­apsid reptiles with awidespread distribution,including South America.The photo is ofPlacerias,from Arizona. Photo byElaine Kennedy.

Geoscience Reports

the Paleogene, and two familiesshared only with northern continents.None of the therapsids or dinosaursis known from Cenozoic deposits.The therapsids (see Figure 5) arewidespread, except for one familyendemic to South America andanother shared only with Africa. Fivedinosaur families are endemic toSouth America, and eight are wide­spread. None is shared exclusivelywith other southern continents.

The remaining families are mis­cellaneous types of reptiles. Fivefamilies are widespread, five areendemic to South America, and fiveare shared only with northern conti-

Extinct Paleozoic andMesozoic Terrestrial Families

Figure 4. Most extinct Paleozoic andMesozoic terrestrial families of SouthAmerica are either widespread or re­stricted to South America.

nents. One is shared only with Africa,and one family ofturtles has a disjunctsouthern distribution that is poorlyunderstood.

In summary, South AmericanPaleozoic and Mesozoic fossils ofterrestrial vertebrates are nearly allfrom extinct families (48/50). Mostare reptiles (39 of 50 families). Theyare most frequently either endemic toSouth America (19 families) or havea widespread distribution, includingboth northern and southern continents(19 families). Nine families areknown only from South America andone or more northern continents. Twofamilies are found only in SouthAmerica and Africa, and a third hasa disjunct southern distribution.

present a problem needing furtherstudy.

4. Neogene terrestrial families

Thirty-eight terrestrial familieshave first South American appear­ances in Neogene sediments.Eighteen of these are living today inSouth America. Rheas, a family oflarge flightless birds, are oneexample. The remaining families aremammals, including 13 familiesendemic to South America and itsmargins (e.g., guinea pigs), and fourwidespread families (e.g., weasels).In general, the endemic familiesappear in the fossil record lower thanthe widespread families.

Twenty extinct families have fIrstSouth American appearances in theNeogene (included in Figure 6). Allare mammals (see Figure 8), and allexcept one are restricted to SouthAmerica or areas marginal to it.Examples include giant sloths and

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Again, northern links outnumbersouthern links.

3. Paleogene terrestrial families

Fossils of forty-eight terrestrialfamilies have first South Americanappearances in Paleogene sediments.Six of these are living in SouthAmerica today - one widespreadfamily of turtles, one widespreadtropical family of amphibians, andfour of mammals endemic to SouthAmerica and its margins.

The remaining forty-two familiesare extinct (see Figure 6 for summaryof Paleogene and Neogene families).Thirty-eight of these are mammalfamilies endemic to South America

Extinct Cenozoic TerrestrialFamilies

Figure 6. Almost all extinct Cenozoicterrestrial families of South America arefound nowhere else, even as fossils.

(see Figure 7), along with one croc­odilian family and one bird family. Asecond bird family is widespread~ anda snake family has a disjunct southerndistribution. Twenty-four families arerestricted to Paleogene sediments,while eighteen families have strati­graphic ranges that extend intoNeogene sediments.

In the view taken here, it isthought that the Paleogene fossilswere organisms killed by the flood.However, some other creationistshave different views on this point. Thefour living mammal families withPaleogene fossils in South America

Figure 7. Toxodon is amember ofan extinct familyof mammals restricted toSouth America. Photo byAriel Roth.

Figure 8. Glyptodonts werevery large mammals resem­bling armadillos. Now extinct,their fossils have been foundfrom Florida through SouthAmerica. Photo byAriel Roth.

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strange hoofed animals. As previ­ously noted, another eighteen extinctfamilies are found in both Paleogeneand Neogene sediments. The onlywidespread extinct family found inSouth America is a group of ele­phants. These elephants first appearin South America in the upper part ofthe Neogene sediments, along withfossils of several widespread livingmammal families. No terrestrialfamilies with fossils restricted to Neo­gene sediments are shared exclusivelywith either northern or southerncontinents.

5. Summary

Most extinct aquatic familiesfound in South America are widelydistributed (9 families) or shared onlywith northern continents (8 families).Three are endemic to South America,one is shared only with Australia, andone is shared only with Africa (seeFigure 2). There is no need to explain

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these distributions in relationship tothe ark, since they are aquatic groups.

Among the extinct terrestrialfamilies, the majority (70/110) arerestricted to Paleozoic through Paleo­gene deposits. Nineteen families arewidespread, seven are shared onlywith northern continents, and threeare shared only with southern con­tinents. The remaining 43 families areendemic to South America. All thefamilies restricted to Paleogene sedi­ments are found only in SouthAmerica and its margins. Since noneof these families is found in the Neo­gene of South America, their distri­butions may be the result of floodactivity.

Twenty extinct terrestrial familiesare restricted to Neogene sediments.All but one these are restricted toSouth America and its margins.Further study is required in order todevelop an explanation for the largenumber of endemic families in Neo­gene sediments. Another eighteenfamilies are found in both Paleogeneand Neogene deposits. These familiespresent another problem requiringfurther study to understand theirdistribution in relationship to theflood. Stratigraphic distributions arealso of interest, but are beyond thescope of this paper.

Discussion

Three predictions about biogeo­graphical patterns were made inPart 1 of this article (see GeoscienceReports No. 25). The first predictionwas that living groups of terrestrialvertebrates should be distributed in amanner that reflects the present con­tinental arrangement, with dispersalfrom the ark. This prediction isstrongly verified. South American ter­restrial vertebrates are most similarto those of North America. The ter­restrial vertebrate fauna of SouthAmerica is markedly different fromthose of Australia and Africa.

The second prediction was thatsome invertebrate and aquatic groupsthat survived the flood outside the arkshould show some distributionpatterns due to oceanic currents, andthis could result in distributionsrestricted to the southern continents(see Figure 9). Data presented inPart 1 showed this prediction to beverified. Several living families arerestricted to South America and oneor more of the other southern con­tinents. None of these groups are ter­restrial vertebrates, and so were notdependent on the ark for survival.

The third prediction was that thosegroups of terrestrial vertebrates re­stricted to the southern continentsshould be extinct groups, not livinggroups. This prediction was partiallyverified and partially refuted. Asexpected, no living South Americangroups of strictly terrestrial verte­brates are shared exclusively withother southern continents. Reasonsfor rejecting ratite birds and marsupialmammals as examples were pre-

Figure 9. Araucaria trees are now. naturally limited to the southern hemi­sphere, but their fossils are widespread.They are once more widespread, due totheir attractiveness tc!" humans. Photo byJim Gibson.

Geoscience Reports

sented in Part 1. Several extinctgroups are shared exclusively withother southern continents, but this isconsistent with the prediction, sincetransport of dead or dying animals byoceanic currents during the floodcould produce such a fossil distri­bution pattern. However, many SouthAmerican terrestrial families arerestricted to South America alone,contrary to the prediction. Theoriginal sources of these groups re­main unknown, and further study isneeded to understand their presentand past distributions.

The Problem ofSouth AmericanEndemism

The major problem for explainingbiogeographical distributions is thelarge number of terrestrial vertebratefamilies that are restricted to SouthAmerica, with no evidence of theirpresence in other areas at any time(see Figure 10). What factors orprocesses might explain the highincidence ofendemism among SouthAmerican terrestrial vertebrates?

At least two suggestions havebeen made to explain the lack ofevidence of dispersal of SouthAmerican mammals from the ark.One suggestion is that humans carriedmammals with them as they dispersedfrom the ark (described in Browne1983:12; see also Woodmorappe1990). Ifthis were the case, one wouldexpect to find such animals as sheepand cattle worldwide. However, thereare no fossil records of sheep or cattlein Australia or South America. It doesnot seem likely that humans carriedarmadillos, sloths and opossums toSouth America. None ofthese has any .significant economic value tohumans. Furthermore, fossil evidencesuggests that the endemic animalsreached South America before anyhumans did.

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Figure 10. The "Patagonian hare"resembles a rabbit, but is actually amember of a rodent family restricted toSouth America. Photo by Jim Gibson.

A second possible explanation isthat the fossil record is too incompleteto record the migrations of animalsafter the flood (Whitcomb and Morris1961:83). Under certain circum­stances, the former presence of agroup of animals in a region mightnot be detectable in the fossil record.This might be expected if the numberof individuals was very small, and/orif the group spent only a short time inthe region.

There are good reasons to supposethat a species could migrate from theark to South America without leavingany evidence. Many fossil species areknown from one or a few occurrences,and the fossil record is obviouslygeographically incomplete. Fossilformation in the present world isrelatively rare, so absence ofevidenceis not the same as evidence ofabsence. An example of the geo­graphical incompleteness ofthe fossilrecord is the discovery of a fossilmarsupial in Thailand (Ducrocq et al.1992). This is the only marsupialfossil known from southeastern Asia.Where did it come from, and how didit get there? A fossil found in Ger­many has been identified as a SouthAmerican type of anteater (Storch1981), although this identification hasbeen challenged (Branham andGaudin 1997). If the identification isaccepted, the German fossil is the

only known evidence ofthe existenceof its family outside ofSouth Americaand its margins. "Horned" turtles areknown only from Paleogene depositsof South America and Quaternarydeposits of Australia and New Cale­donia (Benton 1993). Surely, theremustbe much missing information ontheir distributional history. Manyother examples could be cited to showthat fossils cannot be relied on for acomplete record of a species geo­graphic distribution.

At least two processes relating tothe flood could explain why the fossilrecord mightbe especially incompletewhen the animals were dispersingfrom the ark. First, if certain groupshad an instinctive drive to migratefrom the ark directly to SouthAmerica, they might accomplish suchdispersal in a short time, and with onlya few individuals. It is highly unlikelythat such groups would leave anyfossil evidence of their passagethrough the region. Supernaturaldirection of migration has beenproposed (Whitcomb and Morris1961 :86; the idea is mentioned inBriggs 1995:5).

Rapid changes in climate soonafter the flood are a second factor thatcould result in rapid changes inspecies ranges. For example, if theclimate were becoming cooler, heat­loving species would tend to expandtheir ranges toward the tropics(moving southward) and retreat from

Figure 11. Llamas aremembers of the camelfamily, which is naturallypresent only in SouthAmerica and Asia. Fossilsare widespread, and areespecially diverse in NorthAmerica. Climatic changesin North America may havecontributed to their ex­tinction there. Photo by JimGibson.

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the north (see Figure 11). If thisprocess occurred soon after the flood,species populations might still berelatively low. Groups that lived in aregion for a short time, with low popu­lation levels, might easily escapedetection in the fossil record of thatregion, even though they are knownas fossils from another region.

In summary, it can be said that wedo not know why there are so manyterrestrial families endemic to SouthAmerica. We can postulate somefactors that might provide an ex­planation, but we don't know howvalid they are. The fact remains thatone of our biogeographic predictionswas not verified, and further study isneeded.

Summary and Conclusions

The distribution patterns of livingSouth American plants and animalscan be explained as the result of acomplex interaction of factors,including oceanic currents, con­tinental movements during the flood,and supernatural preservation in theark. The flood destroyed the terr­estrial, air-breathing vertebrates thatwere not in the ark. Plants, inverte­brates, and aquatic invertebratessurvived outside the ark. This wouldexplain why South America, Africaand Australia have dramaticallydifferent bird and mammal faunas,but share many other groups.

Visit our WEB site at ­http://wvvw.tagnet.org/gri/

...for information about GRI (with at least one staff link and moreto come). We also list various News Items that we think are interesting.We have posted them without editorial comments. In addition, welist some GRI Resources that might be helpful to you, such as theindex to Origins and some Topical Papers that can be downloaded.Finally, we have a long list of Other Sites of Interest. We do notnecessarily endorse of any of the links, but if surfers want to knowwhat others are thinking about issues in science and religion, thesesites should provide a broad cross-section of opinion. More paperswill be added.

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A few apparent exceptions to thedestruction of terrestrial vertebrateshave been proposed, based onsouthern distribution patterns. Theseexamples are not convincing becausethey are based on groups (ratites andmarsupials) that may not be genea­logically related, and whose fossilrecord is too incomplete to rule out adispersalist interpretation.

Many plants, invertebrates andmarine vertebrates survived the floodoutside the ark. Those groups that sur­vived the flood may often have distri­bution patterns that reflect either pre­flood geography or oceanic currentsduring or after the flood. This ex­planation would apply to the plants,fish, frogs, turtles and other reptilesthat are found only in South Americaand Africa or Australia.

The most difficult biogeographicdistribution patterns to explain are thelarge numbers of living endemicSouth American terrestrial verte­brates. Most of these have left noevidence of their movement from theark. This may be explained by as­suming that the animals did not leavefossils as they migrated from the ark.This may have been because theirmigration took place over a shortperiod of time, and involved a smallnumber of individuals.

It should be clear that the floodmodel explanation for biogeographicdistributions is incomplete and notwithout problems. Yet it seems to pro­vide a useful, generalized explanationfor the differences in distributionpatterns between aquatic and ter­restrial vertebrates.

Originsstarts at

the beginning

Literature CitedBenton MJ. 1993. Fossil record 2.

London: Chapman & Hall.

Branhan DG, Gaudin TJ. 1997. Thephylogeny of the Myrmecophagidae(Mammalia, Xenarthra, Vermi­lingua) and the relationships ofEurotamandua. Journal of Verte­brate Paleontology 17(3):33A.

Briggs Je. 1995. Global biogeography.Amsterdam: Elsevier.

Browne J. 1983. The secular ark.Studies in the history of biogeo­graphy. New Haven andLondon:Yale University Press.

Carroll RL. 1988. Vertebrate paleon­tology and evolution. NY: W.H.Freeman and Co.

Ducrocq S, et al. 1992. First fossil mar­supial from South Asia. Journal ofVertebrate Paleontology 12:395­399.

Storch G. 1981. Eurotamandua joresi,ein Myrmecophagide aus demEozan der "Grube Messel" beiDarmstadt (Mammalia, Xenarthra).Senckenbergiana Lethaea 61 :247­289.

Whitcomb JC, Morris HM. 1961. TheGenesis Flood. Phillipsburg, NJ:Presbyterian &Reformed Publishers.

Woodmorappe J. 1990. Causes for thebiogeographic distribution of landvertebrates after the flood. In: Pro­ceedings of the Second InternationalConference on Creationism, Pitts­burgh, PA, p 361-367.

Geoscience Reports

EDITOR'S aANGLE

Biogeographic distributions ofterrestrial and aquatic vertebratespose questions about the post-floodredistribution of these organisms.Thesequestions create a springboardfor the development of hypothesesthat may be useful in future researchon this topic. As we seek criteria tobetter define models for post-flooddeposits, such topics urge us to gobeyond the easy answers and to digmore deeply into the data. Discussingthese issues with students providesteachers with an opportunity to in­spire the natural creativity andcuriosity of students while affirmingtheir faith in the biblical record ofearth history. It is our hope that thistwo-part paper on biogeography haspresented both challenges and enrich­ment for SDA junior and senioracademy students.

Students and teachers are en­couraged to discuss this paper furtherwith Dr. Gibson through email:

jgibson@ccmail.llu.eduComments and suggestions with

regard to Geoscience Reports areencouraged:

ekennedy@ccmail.llu.edu

Desde 1982, ellnstituto de Investigaci6n en Geociencia viene publicando un

peri6dico tres veces al ano en castellano. Se llama"Ciencia de los Orfgenes"y su

redactor es el Dr. David Rhys. Cubre extensamente los temas de orfgenes.

La suscripti6n es de $1.50 en los EEUU y Mexico. Para los demas pafses es de

$2.50.

Puede enviarse cheques u 6rdenes de pago en d6lares (no estampillas) a

"Ciencia de los Orfgenes,"Geoscience Research Institute, Loma Linda University,

Loma Linda, CA 92350 USA.

Geoscience Reports

SCIENCE NOTESEditor;s Note: For those who

believe that life on Earth is recent,there are many unsolved scientificquestions. We sometimes find pointsin the scientific literature that are en­couraging and we like to pass onthese to our readers.

GEOLOGY

Alvarez vv, Staley E, O'Connor D,Chan MA.1998. Synsedimentarydeformation in the Jurassic ofsouth­eastern Utah - A case of impactshaking? Geology 26:579-582.

Deformation of the Carmel andEntrada Formations in ArchesNational Park may be due to a postu­lated impact crater at Upheaval Domesouth of Needles, UT. Liquefactionof soft sediments associated with theimpact could explain the fluid-likestructures and pipes ofsand that occurwithin these two formations. Quartz­rich rock fragments and severalstructural features are cited asevidence for an impact crater.

This paper includes summaries offive previous theoretical explanationsfor the large and small-scale soft-

GEOSCIENCE REpORTS Fall 1998 No. 26

Editor Elaine G. KennedyAssociate Editor Katherine Ching

Subscription requests, correspondence, and noticesof change ofaddress should be sent to: PublicationsEditor; Geoscience Research Institute, Lorna LindaUniversity, Lorna Linda, CA 92350 USA. Annualsubscription rate is $3.00 (U.S. currency).

Geoscience Reports is a newsletter published bythe Geoscience Research Institute to presentcurrent happenings at the Institute as well asgeneral-interest articles that deal with creation!evolution issues for elementary/secondary-schooland college science classes. The views expressedare those of the authors and not necessarily thoseof the Institute.

Staffofthe Institute: L Jim Gibson, Director (PhD,biology); Ben L Clausen (PhD, nuclear physics);Elaine G Kennedy (PhD, geology); Clyde LWebster (PhD, chemistry); Katherine Ching, Editor(MA, history); and Janet Williams, AdministrativeSecretary.

sediment deformation visible inArches National Park. Theory 1suggests that the buckling of thelayers is due to compression but thisidea does not explain the occurrenceof structures generated by the move­ment of fluid through soft sediments.Theory 2 ascribes the deformation tosoft sediments sliding down slope;however, there is no evidence ofshearing within the layers of thestructure. Theory 3 proposes thatevaporites dissolved and causedstructural collapse and deformation ofthe layers. This process is too slow toexplain the sandpipes. Theory 4hypothesizes the deformation was dueto loading of the Entrada sandstoneon the Carmel muds and suggests asubaqueous depositional environ­ment for the Entrada Formation. Thisargument is deemed unlikely solelybecause it contradicts the currentlyaccepted eolian (wind-deposited)model. Theory 5 relies on liquefactiondue to earthquake activity; however,there is no evidence of aftershocks.

Comment: For catastrophists allof these theories can be explainedvery well within the context of aworldwide flood. The objections tothe proposed theories, including theimpact theory of this paper, all comefrom the data base associated with thedeformation features, with the ex­ception of Theory 4. This theory wasrejected because it did not fit thecurrent interpretation for an eoliandepositional environment. Such aconclusion is surprising. The data

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base provides a strong argument forsubaqueous deposition.

Nadon Gc. 1998. Magnitude andtiming of peat-to-coal compaction.Geology 26:727-730.

New data and observations ofstructures associated with the for­mation of coal suggest that theprevious compaction values areinflated. 1) Fragments of peat thatwere ripped up and incorporated intothe associated sandstone deposits arenow coal. Compaction ratios for thesefragments should be the same as theadjoining coal beds. Sedimentarystructures in the sands indicate littleor no compaction has occurred.2) Decompaction modeling of coalbeds cut by channel sands producesimpossible sandstone geometries.3) Preservation quality of dinosaurtrackways indicate little compactionof the peat. 4) Dewatering anddestruction by fire of significantamounts of biomass is believed tooccur during the peat stage. Theseprocesses are considered the majorsource of peat "compaction."

Comment: Dewatering is unlikelyto contribute significantly to com­paction of a peat. Fire results in a lossof biomass rather than a compactionof biomass. Little to no compactionrequires less regional subsidence forthe formation of coals since lignitecan form at shallow depths. Thiswould significantly reduce the totalestimated volume required for thebiomass of the preflood world.

8 Geoscience Reports

GEOSCIENCE NEWSNAD TEACHERS' CONFERENCE

NAD teachers examine an outcrop of pillow basalts and palagonite near Vantage,Washington.

In Yakima (WA), on July 13, fortyteachers gathered to begin a fieldstudy of catastrophism in the PacificNorthwest. In addition to the fieldwork, 30 lectures covered a broadrange of topics including issues inbiology, geology and physics. Fieldstudies extended from the ChanneledScablands of central Washingtonwhere coulees, boulders, floodbasalts, and a rhino mold wereexplored. The class then drove westto Mount Rainier and completed theirwork at Mount St. Helens, where theyhiked to Spmt Lake and later visitedthe Johnston Ridge Visitor's Center.

This year the attendees receivedaT-shirt with a logo illustrating the"Rainbow Connection" presented inthe Sabbath sermon, and "polyphyly,"an alternative view of origins. Theyalso received a volume of lecturenotes and 2 videos: "The Eruption ofMount St. Helens" and "The GreatFloods." Course requirements in­cluded field notes from at least3 localities, a video review forpossible classroom use, a book reviewof "Cataclysms on the Columbia" byAllen, Burns, and Sargent, and the

development of a teaching unit oncatastrophism.

Jim Gibson (course instructor),Ben Clausen, Elaine Kennedy (fieldinstructor), and Clyde Webster wereassisted by guest lecturers EarlAagaard from Pacific Union College,John Baldwin and Tim Standish fromAndrews University, and Joe Galushafrom WallaWalla College (Sue Dixon

from Walla Walla presented adevotional). The guest lecturers pre­sented several topics to the class thatgreatly enhanced the quality of theprogram. Their efforts were muchappreciated by the Geoscience staffand the teachers.

is the winner of a Silver Screen award.

This 45-minute video (with a companion all-color magazine) isavailable in VHS or PAL format for U.S. $29.95 + shipping costs.

To order your copy,please contact your local Adventist Book Center

orthe Review and Herald Publishing Association

55 W Oak Ridge Dr., Hagerstown MD 21740 USATelephone: (301) 791-7000

A Teacher's Guide is ayailable from the GRI

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BAUMGARDNER'S MODELING OF RAPIDPLATE TECTONIC MOTION

Ben Clausen, Geoscience Research Institute

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John Baumgardner in his lab at the Los Alamos National Laboratory inNew Mexico. Photo courtesy Public Affairs Office, Los Alamos NationalLaboratory.

Dr. John Baumgardner's earlyroots are from Texas, in a familycasual to the claims ofthe Bible. Afterreceiving a master's degree in electri­cal engineering from PrincetonUniversity, he returned to Texaswhere he became part of a Presby­terian college Sunday school class.Through a verse-by-verse study of theGospel ofJohn, he was led to considerthe question of who Jesus Christ isand had what he calls "a dramaticconversion experience." Having beenwell- schooled in evolution theory, hetook a while to recognize a conflictwith the Bible's portrayal of anoriginally perfect earth, where deathand a catastrophic flood occurred onlyafter sin.

While giving university lectureson creation/evolution topics, hebecame keenly aware of the need forcreationists to provide a geologicalmodel to account for the large-scalemotion of the earth's surface, i.e.,plate tectonics.

In 1983 Baumgardner completedhis Ph.D. in geophysics from theUniversity ofCalifornia, Los Angeles(UCLA) with a thesis entitled, AThree-Dimensional Finite ElementModel for Mantle Convection. Henow continues his modeling of platetectonics as well as other geophysicalfluid dynamics research as a staffmember of the Theoretical Division,Fluid Dynamics Group, Los AlamosNational Laboratory.l,2

To model the motion ofthe earth'splates (roughly equivalent to thecontinents), Baumgardner uses aFortran program called TERRA3,developed originally as part of hisPh.D. research, that must be run on a

supercomputer because of its size andcomplexity. It divides the earth'smantle (a 3000 km layer of rock thatsurrounds the earth's core) intomillions of three-dimensional hexa­gonal cells, each with a variable valuefor its temperature, pressure, density,velocity, and material properties.These variables change through timein a calculation based on a small setof basic principles. TERRA is one offour models in the world capable ofmodeling the earth in a global manner.Results from this computer programhave been presented at the AmericanGeophysical Union meetings4 as wellas being described in scientificjournals.5

Baumgardner's simulation of theGenesis Flood begins with an originalsingle supercontinent that breaks upbecause the surrounding ocean flooris colder, and thus,denser, than therock below it. The more dense surface

rock follows the natural tendency tosink into the hotter, less dense mantlerock beneath it. The drag of thesinking ocean floor pulls the morebuoyant continental plates outwardsfrom the center of the supercontinentresulting in the drift of North andSouth America away from Europeand Africa still seen today. Runawaysubduction, first proposed in the1960s by a physicist at GeneralElectric, allows this movement of thetectonic plates to happen rapidly andis a consequence of the fact thatsilicate minerals weaken dramaticallywith increasing temperature anddeformation rate. By omitting someof the physics of rock deformation,TERRA can model the scientificallystandard slow rates of plate motion.However, when the more detailedphysics is included, Baumgardnerfinds the model predicts much morerapid motion. Details ofhis model for

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the Genesis Flood were presented atthe Third International CreationConference.6

Baumgardner recognizes thatthere are legitimate questions aboutthe physical processes needed toobtain these rapid rates:7 (1) The timeframe for the Flood requires aneffective mantle viscosity [resistanceto fluid flow] almost one billion timessmaller than the estimated presentviscosity. Since viscosity decreasesexponentially with increasing temper­ature and also in a strongly nonlinearmanner with increasing deformationrate, he believes [and recently hasdemonstrated in numerical calcu­lations] that such decreased viscositynaturally o~curs throughout largevolumes of the mantle as the runawayprocess unfolds. (2) The short timescale for plate motion conflicts withthe long time scale implied byradiometric dating, which requires allradioactive decay since the Cambrian[where the lowest major fossil bearingrocks appear] to have taken placesince the beginning of the Flood.Baumgardner believes the nucleardecay rates likely have not beenconstant during the earth's history andwere orders of magnitude higherduring the Flood event. (3) Based onthe normal rate at which rocksconduct heat, millions of years seemto be required for the cooling of theoceanic lithosphere from near themolten state to its current thermalregime. Baumgardner believes thatenhanced cooling rates, as a conse­quence ofhydrothermal circulation ofocean water through the lithosphericlayer, are insufficient to solve theproblem. In addition, a much fastertransfer of heat from the crust intooceans would seemingly produce atemperature for the ocean and atmo­sphere that is too hot for life. 8

Baumgardner concludes that "anenhanced rate ofnuclear decay during

the [Flood] event and a loss ofthermalenergy afterward" "cannot be under­stood or modeled in terms of time­invariant laws ofnature". He believesthat "intervention by God in thenatural order during and after thecatastrophe appears to be a logicalnecessity."

In the Los Alamos community,Dr. Baumgardner is known as aChristian activist, concerned forexample with the dogmatic teachingof evolution as fact in the publicschools, but he does not push hisreligious views on his colleagues.Brad Hager, a geophysicist at Massa­chusetts Institute ofTechnology, saysit would require a miracle to increasethe thermal diffusivity [rate at whichrocks conduct heat] to a level wherethe lithosphere could have cooled ina few thousand years. However,Hager has only respect· for Baum­gardner's computer program. GeraldSchubert, of the UCLA Departmentof Earth and Space Sciences, agreesthat "As far as the code goes, Baum­gardner is a world-class scientist.""Indeed, there is universal agreementthat TERRA, created to prove theBible literally true, is one of the mostuseful and powerful geological toolsin existence."i

ENDNOTES1. Burr C. 1997. The geophysics of God:

a scientist embraces plate teCtonics- and Noah's flood. U.S. News &World Report (June 16) 122(23):55­58.

2. Wieland C, Batten D. 1997. Probingthe earth's deep places: interviewwith plate tectonics expert Dr JohnBaumgardner. Creation ex nihilo(June-August) 19(3):40-43.

3. Web information is available at http://www-igpp.lanl.gov/TERRA.html(on Terra) and at http://curie.eps.jhu.edu/nasa.html (on theHigh Performance Computing inGeodynamics). '

Geoscience Reports

4. (a) Baumgardner J. 1992. 3-Dnumerical investigation of themantle dynamics associated with thebreakup of Pangea. Fall MeetingAbstract Supplement, October 27.Eos, Transactions of the AmericanGeophysical Union 73(43):576;(b) Baumgardner JR. 1994. Thermalrunaway in the mantle. Fall MeetingAbstract Supplement, November 1.Eos, Transactions of the AmericanGeophysical Union 75(44):687.

5. (a) Bunge H-P, Richards MA, Baum­gardner JR. 1996. Effect of depth­dependent viscosity on the platformof mantle convection. Nature 379(1 February):436-438; (b) see also:Computer replicates Pangea's break­up. Geotimes 38(3):9; (c) Beard J.1993. How a supercontinent went topieces. New Scientist 137(1856,16 January): 19.

6. (a) Baumgardner JR. 1994a. Com­puter modeling of the large-scaletectonics associated with theGenesis Flood, and Runaway sub­duction as the driving mechanismfor the Genesis Flood. In Walsh RE,editor. Proceedings of the ThirdInternational Conference on Cre­ationism. Pittsburgh: CreationScience Fellowship, p 49-62;(b) Baumgardner JR. 1994b.Runaway subduction as the drivingmechanism for the Genesis Flood.In Walsh RE, editor. Proceedings ofthe Third International Conferenceon Creationism. Pittsburgh: CreationScience Fellowship, p 63-75.

7. Baumgardner JR. 1986. Numericalsimulation of the large-scale tectonicchanges accompanying the Flood. InWalsh RE, Brooks CI, Crowell RS,editors. Proceedings of the FirstInternational Conference on Cre­ationism. Pittsburgh: CreationScience Fellowship, p 17-30.

8. Barnes RO. 1980. Thermal conse­quences of a short time scale for sea­floor spreading. Journal of theAmerican Scientific Affiliation32: 1123-125.

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