ThespeculationsofDeMailletinthebeginningoftheeighteenthcenturyturnuponfossils;andBuffonfollowshimverycloselyinthosetworemarkableworks，the\"TheoriedelaTerre\"andthe\"EpoquesdelaNature\"withwhichhecommencedandendedhiscareerasanaturalist。
Theopeningsentencesofthe\"EpoquesdelaNature\"showushowfullyBuffonrecognisedtheanalogyofgeologicalwitharchaeologicalinquiries。\"Asincivilhistoryweconsultdeeds，seekforcoins，ordecipherantiqueinscriptionsinordertodeterminetheepochsofhumanrevolutionsandfixthedateofmoralevents;so，innaturalhistory，wemustsearchthearchivesoftheworld，recoveroldmonumentsfromthebowelsoftheearth，collecttheirfragmentaryremains，andgatherintoonebodyofevidenceallthesignsofphysicalchangewhichmayenableustolookbackuponthedifferentagesofnature。Itisouronlymeansoffixingsomepointsintheimmensityofspace，andofsettingacertainnumberofwaymarksalongtheeternalpathoftime。\"
Buffonenumeratesfiveclassesofthesemonumentsofthepasthistoryoftheearth，andtheyareallfactsofpalaeontology。
Inthefirstplace，hesays，shellsandothermarineproductionsarefoundalloverthesurfaceandintheinteriorofthedryland;andallcalcareousrocksaremadeupoftheirremains。
Secondly，agreatmanyoftheseshellswhicharefoundinEuropearenotnowtobemetwithintheadjacentseas;and，intheslatesandotherdeep—seateddeposits，thereareremainsoffishesandofplantsofwhichnospeciesnowexistinourlatitudes，andwhichareeitherextinct，orexistonlyinmorenorthernclimates。Thirdly，inSiberiaandinothernorthernregionsofEuropeandofAsia，bonesandteethofelephants，rhinoceroses，andhippopotamusesoccurinsuchnumbersthattheseanimalsmustoncehavelivedandmultipliedinthoseregions，althoughatthepresentdaytheyareconfinedtosouthernclimates。Thedepositsinwhichtheseremainsarefoundaresuperficial，whilethosewhichcontainshellsandothermarineremainsliemuchdeeper。Fourthly，tusksandbonesofelephantsandhippopotamusesarefoundnotonlyinthenorthernregionsoftheoldworld，butalsointhoseofthenewworld，although，atpresent，neitherelephantsnorhippopotamusesoccurinAmerica。Fifthly，inthemiddleofthecontinents，inregionsmostremotefromthesea，wefindaninfinitenumberofshells，ofwhichthemostpartbelongtoanimalsofthosekindswhichstillexistinsouthernseas，butofwhichmanyothershavenolivinganalogues;sothatthesespeciesappeartobelost，destroyedbysomeunknowncause。Itisneedlesstoinquirehowfarthesestatementsarestrictlyaccurate;theyaresufficientlysotojustifyBuffon’sconclusionsthatthedrylandwasoncebeneaththesea;thattheformationofthefossiliferousrocksmusthaveoccupiedavastlygreaterlapseoftimethanthattraditionallyascribedtotheageoftheearth;