544 



CENOZOIC TIME. 





dropped by the glacier, after the period of melting set in, over the 

 hills where there were no waters to receive them, and which are, 

 therefore, unstratijied ; and (2) those which fell into waters, or where 

 the waters could gather them up for transportation, and which there- 

 fore became more or less stratified. In other words, the unstratijied 

 and stratified Drift, as stated on page 527, were deposited mainly in 

 the Diluvian era of the Champlain period. 



To the Alluvian era belong the subsequent deposits of the period. 



In both eras, there were, outside of Glacial latitudes, and partly 

 within, other formations of various kinds in progress, like those oi 

 the present day. 



A. Unstratijied Drift. — The unstratiiied Drift consists of sand, 

 gravel, stones, lying pell-mell together, as they were thrown down 

 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 (1) along the valleys and flooded streams; or 

 (2) in and about flooded lakes ; or (3) in estuaries, and along sea- 

 borders ; making (1) Fluvial, (2) Lacustrine, and (3) Sea-border for- 

 mations. 



2. Fluvial and Lacustrine 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. Distribution. — The fluvial and lacustrine formations appear to 

 characterize all the river-valleys and lake-basins of the continent, over 

 the Drift latitudes, and also, to a less extent, those still farther south, 

 so that they may be said to have a continental distribution. The 

 fluvial deposit generally accompanies the whole course of a stream 



