554 CENOZOTC TIME. 



There is direct evidence that the flood reached a maximum just be- 

 fore the close of the melting. In some of the New England estuaries, 

 of the Champlain era, as that of New Haven (and it may be true of 

 all), the stratified deposits are mainly of sand and small pebbles, until 

 within fifteen or twenty feet of the top. But, above this limit, there 

 is a sudden change, especially along the courses of the streams enter- 

 ing the estuary, to very coarse gravel, the stones in it often four or 

 five inches through ; a change which indicates that, when the flood 

 was at its height, the torrent bore off thence the sand and fine gravel, 

 and dropped chiefly the stones. The finer material was carried to the 

 west side of the lower part of the New Haven estuary, where the de- 

 posits, through their whole height, are of sand. 



The sand deposits which succeed the " Erie clays," in the region 

 of the Great Lakes, may be evidence of the flood over those regions. 

 The logs and vegetable debris, which in some spots top the clay beds, 

 (p. 546) may be additional proof of the loosened grasp of the ice» 

 The depositions of Orange sand along the Mississippi valley probably 

 took place at this time of maximum flood. 



There is other evidence of this climax in the flood. As stated on page 549, the lam- 

 inae of the obliquely laminated layers, in the stratified deposits of the New Haven plain, 

 rise to the northward, as a consequence of their deposition by the in-flowing tidal current. 

 The flooded rivers brought down the sand and gravel ; and the tidal flow determined 

 the deposition of it. But, over the regions where two of the river valleys pass into the 

 New Haven plain, while the northward-rising or tide-made lamination characterizes 

 the lower part of the deposit, the upper fifteen to twenty fleet has the lamination reversed, 

 the lamina rising to the south, showing that these were deposited by the river flood. 

 The transition was a sudden one, as the abrupt transition in the beds proves. It is 

 marked also in a change in the color of the sands, from a reddish to a brownish yellow. 

 This change was not owing to a shallowing of the waters ; for in most parts of the 

 estuary region, the tide-made oblique lamination characterizes the beds to the top of 

 the formation. 



Thus we learn that the flood finally rose to a height which enabled the river flow to 

 overpower the tidal and put its own impression on the deposits, besides making coarse 

 pebble beds where the torrent was most powerful. 



The flood would have continued long into the Alluvian era, on ac- 

 count of the ice to the north, yet with much abatement of its violence. 

 Even till near its close, the melting glacier about the northern margin 

 of the Great Lake region may have sent off floating masses down the 

 Mississippi valley, as well as to parts of the present prairie region of 

 Ohio, Indiana, and Illinois. 



Exterminations by the cold waters. — While the reinforced Lab- 

 rador current of the Diluvian era drove Arctic and Subarctic marine 

 species southward along the northern coasts, the ice and ice-cold 

 waters of rivers carried destruction to the life of more southern seas. 

 Professor Hilgard states that the Orange sand or stratified Drift of 

 the Mississippi valley, where it enters the Mexican Gulf, contains no 

 traces of marine fossils, and for the reason that the great ice-cold 



