Succession of Epochs, Glacial and Fluvial Dejjosits, and 



Epochs. 



Eastern Provinces and 

 New England. 



Middle and Southern 

 Atlantic States. 



Recent or 



Terrace. 



(Mostly within the 

 period of tradi- 

 tional and writ- 

 ten history.) 



Rise of the land to its present 

 height, or somewhat higher, soon 

 after the departure of the ice. 

 Rivers eroding their glacial flood- 

 plains, leaving remnants as ter- 

 races. Warmer climate than now. 

 probably due to greater Gulf 

 Stream, formerly permitted south- 

 ern mollusks to extend to Gulf of 

 St. Lawrence, now represented by 

 isolated colonies. 



Continued subsidence of const 

 at New York and southward, and 

 rise of the mountainous belt, by 

 displacement along the fall line 

 of the rivers. Much erosion of 

 the Columbia formation since cul- 

 mination of second Glacial epoch; 

 sedimentation in bays, sounds, 

 and estuaries. 



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Champlain. 



(Close of the 

 second Glacial 

 epoch.) 



Land depressed under ice- 

 weight ; glacial recession ; con- 

 tinued deposition of upper till 

 and deep flood-plains of gravel, 

 sand and clay (modified drift). 

 Terminal moraines markingpauses 

 or readvance during general re- 

 treat of ice. Marine submergence. 

 150 to 230 feet on coast of Maine, 

 to 520 feet in Gulf and valley of 

 St. Lawrence. 



Less subsidence in latitude of 

 New York and southward than at 

 north ; lower Hudson Valley, and 

 part of its present submarine con- 

 tinuation, above sea-level. Gravel 

 and sand deposits from englacial 

 drift in Delaware and Susquehan- 

 na Valleys, inclosing abundant 

 human implements at Trenton, 

 N.J. 



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Second 

 Glacial. 



Second great uplift of the land, 

 3.000 to 4,000 feet higher than 

 now; snowfall again all the year; 

 ice probably two miles thick on 

 Laurentide highlands, and extend- 

 ing somewhat farther south here 

 than in first glaciation. Lower 

 till (ground moraine), and upper 

 till (englacial drift). Terminal 

 moraines, kames, osars, valley 

 drift. 



Renewal of great continental 

 elevation (3.000 feet in latitude of 

 New York and Philadelphia), of 

 excessive snowfall and rains, and 

 of wide-spread fluvial deposits, the 

 Columbia formation, on thecoastal 

 plain, during early part of this 

 epoch. Implements of man at 

 Claymont, Del. 



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Inter- 

 glacial. 



(Longest epoch 

 of this era.) 



Ice-sheet melted here ; proba- 

 bly not more ice in arctic regions 

 than now. 



Fluvial and lacustrine deposits 

 of this time, with those of the 

 first Glacial epoch, were eroded 

 by the second glaciation. 



Depression, but generally not to 

 the present level. Deep channels 

 cut in the bed-rocks by the Dela- 

 ware, Susquehanna, Potomac, and 

 other rivers. The Appomattox 

 deposits much eroded. 



Relative length of this epoch 

 made known by McGee lroin 

 study of this region. 



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First 

 Glacial. 



v. 



Begun by high continental up- 

 lift, cool climate and snowfall 

 throushout the year, producing 

 ice-sheet. Much glacial erosion 

 and transportation; till and strati- 

 fied deposits. Ended by depres- 

 sion of land ; return of warm cli- 

 mate, with rain; final meltine of 

 the ice. Isthmus of Panama 

 probably submerged (Gulf Stream 

 smaller), and again in second 

 Glacial epoch. 



Continental elevation ; erosion 

 of Delaware and Chesapeake Bays, 

 and of Albemarle and Pamlico 

 Sounds. Plentiful snowfall on 

 the southern Appalachian Mount- 

 ains ; snows melted in summer, 

 and heavy rains, producing broad 

 river-floods, with deposition of the 

 Appomattox formation. 



