130 ROCHESTER ACADEMY OF SCIENCE. 



(oil our area). The material of the ridge is mostly gravel, with 

 typical beach structures, well shown where the Sea Breeze trolley 

 line cuts through the bar (or long spit) east of Irondequoit, in the 

 gravel pits of the Sodus railway above Glen Edyth, at the deep pits 

 east of Portland Avenue, where the gravels rest on the bedrock with 

 no intervening till, and finally in the Heft'er pits west of Portland 

 Avenue where dune sands overlie the gravels. 



The size and strength of these gravel bars and embankments 

 indicate that they are the finished product of wavework in a long- 

 lived water body. They are far larger and stronger than the cor- 

 responding features of Lake Ontario, a few miles away, for which 

 two explanations have been suggested, — first that here Iroquois 

 was practically stationary at one level throughout most of its long 

 life time, whereas Ontario has constantly advanced upon newly 

 submerged land surface ; and second that Iroquois found a much 

 larger amount of glacial gravels and other incoherent debris ready 

 to handle, while Ontario is cutting chiefly into stift' delta clays or 

 compact till robbed of its loose surface materials by former lowering 

 v.aters and subsequent land drainage. The value of the former sug- 

 gestion is now somewhat open to doubt (sec page ifjoj and Prof. 

 Fairchild now considers the latter as the real reason. 



The freshness of these beaches in spite of the time that has 

 elapsed since the waves last caressed them is indeed astonishing. 

 With one exception erosion has been impotent against them. This 

 exception is a quarter mile strip between the Sea Breeze trolley line 

 and the road to the Newport House, where the "ridge" has been 

 undermined and carried away by the encroachment of a huge gully 

 v^orking back from the Bay. The terminus of the long spit was not 

 at the trolley, as the contours would suggest, but in the vineyard 

 overlooking the Newport House, — a point that commands the entire 

 Bay. Here the gravel ridges curve around to the south and decline 

 to their final termination. It is evident that neither they nor the 

 silts upon which they were pushed out ever went further at this 

 particular point or connected across the chasm with the companion 

 ^^pit on the east shore, with which they are in line. 



Ncicfaiic beach at Rochester. Westward of our meridian, in 

 the Niagara district, there has been recognized a lower, earlier 



