Topographical Features of the N^ew Haven region. 99 



4. That not more than 1 foot a mile of the increase in the angle of 

 the slope is due to a northward increase in the amount of elevation. 



5. That part of the rapidity of slope in the lower portion of the 

 plain below 40 feet in height, after allowing for a descent of the one 

 foot a mile of §4, is due to tidal, wave, and river action over the region 

 of the bay ; and part to increasing depth over the borders of the bay 

 southwai'd ; part to a decrease southward in the amount of transported 

 sand. 



6. That part of the slope in the lower part of the plain may possibly 

 be owing to a slow sinking of the land along the margin of the Sound ; 

 but that there is no evidence that such a sinking is now in progress. 



7. That the level of the terrace along Mill River above Whitney- 

 ville, and along the Quinnipiac north of North Haven may owe 3 or 

 4 feet of its height, as compared with that more to the south, to the 

 fact that the surface of the latter was subjected to wave action be- 

 cause within the range of the bay. 



But may not this rise of 50 feet be only the final condition after a 

 series of oscillations of level? May not the land, when in course of 

 elevation, have risen beyond 50 feet, even to 100 feet or more, and 

 afterward have subsided to the present level ? It is possible ; for such 

 an oscillation as this, performed in a brief period of time, would have 

 passed unregistered. That the land has not stood at a level of 100 

 feet or so for any great length of time in the Recent or Terrace era 

 may be inferred from the fact that, both at the outlet of Saltonstall 

 Lake, and at the passage of Mill River through the Whitneyville gap, 

 the trap dike over which the waters flow has not been worn away 

 below high tide level. The gap intersecting the trap dike, (in fact a 

 trap ridge) was in each case worn down toward its present condition 

 in the Glacial era, as already observed. It is not at all probable that 

 an elevation of the land could have again exposed both these valleys 

 through a long period to the wear of waters flowing along them in 

 rapids and descending in cascades of 50 feet or more, without at least 

 one of them being worn to a lower level. The trap at Saltonstall 

 Lake is soft and easily decomposable. 



The rapids on West River for a mile above the bridge at West- 

 ville, are evidence that the channel has not been excavated, since the 

 Glacial era, to a depth much below the present bottom. 



It has been already stated that large stumps and logs occur in the 

 Quinnipiac meadows. I am informed that it is a common thing to 

 see them projecting from the banks at the very lowest limit of low 

 water, or 5 or 6 feet below the level of the meadows ; and some have 

 been taken out and sawed into good boards. The wet meadows along 



