544 



CENOZOIC TIME. 



from the melting glacier. The bed of bowlder-clay, in progress of dep- 

 osition during the whole progress of the glacier (p. 527), would have 

 continued to increase through the first part of the melting, and after- 

 ward become covered with coarser material. Wherever, in the prog- 

 ress of the deposition over the hills, a temporary run of water was 

 made, some stratification would have ensued; and, if the run was 

 afterward obliterated, the deposition would have been again unstratified. 

 The vegetable material in the ice would have been dropped when- 

 ever the ice relaxed its grasp ; and, being in the lower part of the 

 glacier, and often in large amount at a common level, it would natu- 

 rally have often found lodgment in the lower half of the Drift deposits, 

 either as isolated logs, or as thin beds of vegetable debris. 



B. Stratified Drift and Alluvial Beds. — The material of the strati- 

 fied Drift was derived by the waters either (a) direct from the melting 

 glacier ; or (b) from the loose material that remained over the hills 

 after the ice had disappeared ; or (c), for the later Champlain depo- 

 sitions, in part from subsequent wear and decomposition. The beds 

 were deposited either (d) along the valleys and flooded streams ; or 

 (e) in and about flooded lakes ; or (/) in estuaries, and along sea- 

 borders. 



Fig. 941. 

 B 



Terraces on the Connecticut River, south of Hanover, N. II. 



2. River-border and Lake-border Formations. — The formations of 

 river-borders and lake-borders are essentially alike, except that the 

 latter are, to a greater extent, of a clayey nature. The rivers were 

 often lakes at intervals. 



1. Topographical features. — The fluvial and lacustrine formations 



