THK SUCC'KSSIOX OK I )K I 'OS ITS. 



36 



Ciirilif/irdii lt> ii'itiii. 

 prolitiMy fui'iiu-il ut this tiiiio, 

 tliougli ix'i'liapH in part diiritig the 

 Hcroiul iniixiniiiin of glaciiitioii, 



l'(!iii;\vc(l I'k'vatioii of tliu Coi'- 

 (lilli'iaii region witli oiio well 

 inai'i<u(l paiiHu, during wiiicii tlit; 

 littoral stood aliout "JdO feet 1o\m'I' 

 than at pri'scnt. (ilai'icis nnifli 

 reduced and diminishing, in eon- 

 Hei|Uenee of general anielioiation 

 of climate toward the clo.se of the 

 glacial period. 



I'njiiiii o/ lite (in III /'/iiiii.i, 



Mhore line during thi8 perioil of 



re.st. 



Simultan(!ou.s elevation of the 

 great plains to aliout their pren- 

 enl le\el, witii final exeluHion of 

 waters in conm^cl ion with the sea. 

 Lak(' .\gassiz fornieil and even- 

 tually di'aiued toward tlu^ close (jf 

 this period. This simullaneMua 

 movement in tdcvation of Itoth 

 great areas may prohahly he con- 

 nected with tilt! moi'e general 

 northern elevation of laml at tiie 

 olose of the glacial period. 



The tciidciicy of rt'cuiil oUscrvatioiis Ini.s ln'cni to show 

 that the I'liocuiii' and older siili(h\i.sioii.s ot" th(( 'I'eiliury 

 covered each of them a iinieh h)iiot',r Lime than the 

 I'leistoeene, and that the close of the latter approaches 

 more nearly to the modern or recent time tjian had 

 ])revionsly heen .sn]»])(xsed. 'I'o tlut.se i)oint.s we shall have 

 occasion to refer in tlu; se(|md. 



It may be i)ro])er here to indicate the ,n'eneral nomen- 

 clature which will be followed. When tlu; whole oeoloojeal 

 series is divided into Primary, Secondary and Tertiary, 

 the deposits to which this ])aper relates are usually named 

 Tost-tertiary or C^)iiaternary. These terms arc, in nty 

 judgment, unfortunate and misleadinj:-. If we take the 

 relations of fossils as our guide, then, as Fictet has well 

 remarked, whether we reoard the land or the sea aniniids, 

 there is no decided break between the newer Pliocene 

 and the Pleistocene, the changes not being greater than 

 those between the Pliocene and the older Tertiary ages. 

 There is, therefore, no such thing in natui'e as a (^)uater- 



