238 
port. Not until we succeed in establishing; an absolutely reliable time 
scale for the period between the Ice Ag:e and the beginnings of written 
history, will our estimates of the antiquity of many pre-European 
sites, and of the length of time the Indians have occupied America, 
be any more than guesses. 
Leaving our second problem only partly answered let us take 
up the third, wliat route or routes did man use in coming to America. 
During a part or parts of Pleistocene time northeastern Asia seems 
to have been joined to Alaska, providing an easy passage for the 
migration of the bison, reindeer, and other animals into America. If 
man did actually inhabit this continent during that periorl, he must 
surely have taken the same route, because it offered him tlie only land 
connexion then in existence, and witli the taimitive tools at his com- 
mand he could hardly have built an ocean-going vessel. The bridge 
was severed some time during the latter part of the Pleistocene, 
leaving the present narrow strait that mutes the Arctic ocean with 
the Bering sea. But whether it persisted until most of the ice-sheet 
retreated, and so was available for the passage of early man from 
northeastern Asia into America, remains as yet uncertain. 
Of the other land connexions between America and the Old 
World none endui-ed later, apparently, than tlie Aliocene.^ Man 
was still unborn when Antarctica broke away from South America, 
so that it is idle to speculate on human migrations between the two 
hemispheres along that route. North 7\merica, Greenland, Iceland, 
and Europe may liave been joined together in the early Teritary, but 
we may be sure that no dim tradition of their union inspired Plato’s 
fanciful story of Atlantis, that mythical continent buried beneath 
the ocean, which I^ewis Spence has recently resurrected to explain 
the rise of the Mayan civilization.- The submerged archipelagos, or 
perhaps continents, in the Pacific, postulated by Macmillan Brown in 
order to link the scattered South Sea islands with one another, and 
with Asia and South America, find little or no support among com- 
petent geologists.’^ Such theories of submerged continents over which 
man could wander back and forth throughout the globe naturally 
1 Matthew, W. D. : “Hypothetical Outlines of the Continents in Tertiary Times"; Bull. Am 
Mus. Nat. HLst., vol. 22. pp. 353-383 (New York, l't06). Seott, W. B. : “ The Origin of the Mammal- 
ian Fauaas of North and Soutli America”; Dollo-Festschrift der Palacobiologica, pp. 254-262 (Wien 
und Leipzig, 1928). 
2 Spence, Lewis; "The Problem of Atlantis,” London, 1924. 
3 Brown, J. Macmillan; “Peoples and Problems of the Pacific,” vol. i, ch. xx (London 1927) 
