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



The courses of the tidal currents of the bay are also apparent in 

 the less height of the drift formation wherever they swept along. 

 Thus, within the range of the Mill River tidal course, at Neck Bridge, 

 the heiglit of the terrace on the loest side of the river is but 32 feet, 

 while it is 42 feet on the east side. This Mill River tidal current, 

 although strongest, perhaps, to the west of Franklin street, had a wide 

 spread to the eastward. For the area over which the terrace formation 

 is below its normal height includes not only a region west of Franklin 

 street, but all east of it to the river, and even a large part of 

 Grape Vine Point (the wide point of land between Mill River and the 

 Quinnipiac). Near the bridge at the foot of Chapel street on this 

 Point the height of the drift or terrace formation is only 12 feet, and 

 between this and the southern extremity of the Point, it is still less ; 

 half across the Point in the same line, it is only 21 feet: and half a 

 mile to the north, near the Barnesville or Grand street bridge (the sec- 

 ond bridge over Mill River), the height is only 29 feet. On the Quin- 

 nipiac side of Grape Vine Point, on the contrary, the plain has its full 

 height, being 34 feet in the same east-and-west line with the Chapel 

 street bridge, and 40 feet in that with the Grand street bridge. It is 

 evident therefore that the central part of the great tidal wave up the 

 bay in tbe Champlain era swept northward between Meadow street on 

 the west and Ferry street in Fair Haven (on Grape Vine Point) on the 

 east, an area over 1^ miles wide ; that it continued to be felt on 

 the east side of the river to the north of Barnesville bridge ; but at 

 Neck bridge, approaching the south point of the East Rock range, it 

 was pushed more to the westtcard, the terrace on the east bank at this 

 point having a height of 42 feet, or the full normal elevation. An 

 eastern branch of the tidal wave entered the Quinnipiac basin through 

 the broad channel which forms the lower part of this river. Owing 

 to the bend to the westward in the lower part of this channel, the 

 wave was thrown against the eastern shore, so that the terrace forma- 

 tion on that side is mostly wanting while built up neai'ly to its full 

 height apparently on the western side of the channel even quite to its 

 mouth. 



By closely studying the nature of the stratification of these deposits 

 beneath the New Haven plain, the particular character of the action 

 of the waters may generally be made out, even, in some cases, to dis- 

 tinguishing the effects of individual waves and changes in the action 

 of tidal or river currents. A good example of this is afforded in the 

 region south of the East Rock range (or of Snake Rock, its southern 

 termination) between jNlill River and the Quinnipiac, where sections of 

 the deposits have been made in grading for the Hartford and Air-Line 



