82 J. D. Dana on the origin of some of the 



much as the hills and valleys were everywhere left by the glacier 

 loaded with sand and gravel ready and convenient for transportation. 

 The evidences of rapid deposition are so many and obvious that 

 they appear to set aside any theory of the glacial cold which demands 

 a slow decline of the era. 



2. Later events and results of the Champlaiu era. 



1. Continuation of the Drift formation. — It has been stated that, 

 during the progress of the depositions by the melting glacier in the 

 bay, the lighter or finer portions would have been largely sifted out 

 by the moving waters ; and while part of the sands would have been 

 eddied off to one side, a much larger part would have gone with the 

 current and the ebbing tide down the bay to be distributed by the 

 tides chiefly at their influx along its borders. 



Over the whole of the wide western portion of the New Haven 

 pltein, and especially the southwestern, the terrace formation consists 

 of sands. To the north, toward Westville, at the entrance to West 

 River valley, there are pebbly layers ; but, on passing southward, 

 these rapidly lose most of their pebbly character, and increase in fine- 

 ness ; and between Congress Avenue and Oyster Point, the beds are 

 almost solely sand. The detritus which is now borne by the rivers to 

 the bay is distributed largely along its western side, and there, 

 consequently, are the great sand flats ; and this is so because the di- 

 rection of the tidal current in the Sound on its influx is to the west, 

 and as it entei'S the bay to the northwest ; and the depositions of de- 

 tritus take place mainly during the inflowing tide. The same would 

 have been the action of the currents and tides in the Champlain era ; 

 and hence this western part of the New Haven region would have 

 been, from the beginning of the depositions, an area of accumulating 

 sa7id beds. 



The part of these sand beds that were made during the progress of 

 the melting, should be marked off, if they could be distinguished, as 

 belonging to the first section of the Champlain era, and only the sub- 

 sequent additions, as " later results ;" but the progress of the beds 

 through the two intervals was continuous, and it is probably impossi- 

 ble to ascertain the limit between them. The hills and valleys, after 

 the melting was completed, would in many places have been left thick- 

 ly covered with sand and gravel ready for transportation by every lit- 

 tle rill the rains might make, and the rivers would for a considerable 

 time have continued to transport an unwonted amount of sand. The 

 depositions along the borders of the bay for a while would, therefore, 

 have gone forward with a rapidity almost equalling that of the melt- 



