and Deposits of Flooded Rivers. 51 



Changes in Altitude and Clima.te, during the Quaternary Era. 



Mississippi Basin and 

 northward. 



CORDILDERAN REGION. 



Europe and Asia. 



Terracing of river valleys. 

 Northward rise of area of 

 Lake Agassiz nearly com- 

 plete before the ice was 

 melted on the country 

 crossed by Nelson river; but 

 rise about Hudson bay is 

 still going on. 7,000 to 8,000 

 years since ice-melting un- 

 covered Niagara and falls 

 of St. Anthony. 



Abundant deposition of 

 englacial drift. Stone im- 

 plements in river gravels of 

 Ohio, Ind., and Minn. Lau- 

 rentian lakes held at higher 

 levels, and Lake Agassiz 

 formed in Red river basin, 

 by barrier of retreating ice, 

 with outlets over lowest 

 points of their present 

 southern water-shed. Ma- 

 rine submergence 300 to 500 

 feet on southwest side of 

 Hudson bay. 



Including a stage of con- 

 siderable uplift, with return 

 of humid conditions, alpine 

 giaciation (third Glacial 

 epoch), and the second great 

 rise of Lakes Bonneville 

 and Lahontan. Very re- 

 cent subsidence and change 

 to present aridity. 



Depression probably al- 

 most to the present level. 

 Restoration of arid climate; 

 nearly or quite complete 

 evaporation of Lakes Bon- 

 neville and Lahontan. For- 

 mation of the " adobe " con- 

 tinuing through the second 

 Glacial, Champlain and Re- 

 cent epochs. 



Erosion and terracing of 

 stratified drift in river val- 

 leys. Land passage of Eu- 

 ropean flora to Greenland ; 

 succeeded by subsidence 

 there, admitting warm cur- 

 rents to Arctic sea. Minor 

 climatic changes, including' 

 a warmer stage than now. 

 Upper and outer portions 

 of Indo-Gangetic alluvial 

 plain ; extensive deposits of 

 Hwang Ho, and destructive 

 changes of its course. 



Final departure of the 

 ice-sheets; glacial rivers 

 forming- eskers and kames. 

 Loess deposited while the 

 region of the Alps was de- 

 pressed lower than now. 

 Upper (englacial) till, and 

 asar, of Sweden. Marine 

 submergence 500 to 600 feet 

 in Scotland, Scandinavia, 

 and Spitzbergen. 



Ice-sheet here less exten- 

 sive than in the first Glacial 

 epoch, and not generally 

 bordered as then by lakes 

 in valleys which now drain 

 southward. 



Terminal moraines at ex- 

 treme limit of the ice-ad- 

 vance, and at ten or more 

 stages of halt or re-advance 

 in its retreat. 



Probable uplift 3,000 feet, 

 shown by submerged val- 

 leys near Cape Mendocino. 

 Second ice-sheet on British 

 Columbia and Vancouver 

 island; local giaciation of 

 Rocky Mts., Cascade range, 

 and Sieri-a Nevada, south 

 to lat. 37°. First great rise 

 of Lakes Bonneville and La- 

 hontan. 



Depression nearly t o 

 present level southward ; 

 more northward, but fol- 

 lowed there by differential 

 uplift of 800 or 1,000 feet, 

 Great erosion of loess and 

 other modified drift, and of 

 " Orange Sand." Valleys of 

 this epoch, partly filled with 

 later till, are marked by 

 chains of lakes in southern 

 Minnesota. 



Pliocene elevation of con- 

 tinent brought to culmina- 

 tion at beginning of Quater- 

 nary era; this whole basin 

 probably then uplifted 3,000 

 feet; excessive snowfall and 

 rain; deposition of the 

 "Orange Sand. 1 ' Ice-sheet 

 south to Cincinnati and St, 

 Louis, at length depressing 

 the earth's crust beneath 

 it; slackened river floods 

 and shallow lakes, forming 

 the loess. 



Continental depression. 

 Arid climate. Long contin- 

 ued denudation of the 

 mountains; resulting very 

 thick subaerial deposits of 

 "•adobe." 



Intermittent volcanic ac- 

 tion in various parts of this 

 region, throughout the 

 Quaternary era to very re- 

 cent times, and liable to 

 break forth again. 



Second elevation and gen- 

 eral giaciation of north- 

 western Europe; the ice- 

 sheets of Great Britain 

 probably more extensive 

 than in first Glacial epoch. 

 Oscillations of ice-front ; 

 British Lower and Upper 

 bowlder-clays, the Chalky, 

 Purple and Hessle bowlder- 

 clays. Terminal moraines 

 in Germany. 



Recession, or probably 

 complete departure, of the 

 ice-sheets. 



Land connection between 

 Europe and Africa, permit- 

 ting southern animals to 

 extend far northward. 



Erosion of the Somme 

 valley below its oldest im- 

 plement-bearing gravels. 



Latest rise < 3,000 feet) of 

 the Colorado Canon district. 

 Sierra Nevada and other 

 Great Basin mountain 

 ranges formed bv immense 

 uplifts, with faulting. Cal- 

 ifornia river- courses 

 changed; human bones and 

 implements in the old river 

 gravels, lava-covered. Ice- 

 sheet on British Columbia; 

 local glaciers southward. 



Uplift and giaciation of 

 northwestern Europe; max- 

 imum elevation 2,500 feet or 

 more (depth of the Skager 

 Rack) ; France and Britain 

 united with the Feeroe isl- 

 ands, .Iceland and Green- 

 land. Uplifts of the Hima- 

 layas and other mountain 

 ranges attendant on both 

 Glacial epochs. 



