DELTAS AND DUNES. 45 



This ridge may prove to have been an ancient beach, but its slope towards the 

 interior and its singularity have led me to refer it to a submarine origin. Others, 

 doubtless, will be found along the coast. 



3. Osars. 



I have perhaps already said all that is necessary as to the existence of Osars in 

 this country. I cannot see why they should not occur here as well as in Europe, 

 since all the other forms of modified and unmodified drift are so similar on cis- 

 atlantic and transatlantic shores. But what I call Moraine Terraces cannot be 

 referred to accumulations of detritus by a current sweeping past an obstruction ; 

 and, therefore, they are not osars, if such a mode of formation be essential. I 

 should be inclined to refer to osars those remarkable trains of blocks, starting in 

 Eichmond in Berkshire county, and extending southeasterly several miles, de- 

 scribed by me in the American Journal of Science, XLIX, 253 ; but they are too 

 long to answer Murchison's description. I will mention one or two cases, how- 

 ever, in the vicinity of the White Mountains, which seem to me more like osars 

 than any examples I have met with in this country, though not satisfied that they 

 are so ; but I have placed them on Plate III, in order to call the attention of 

 geologists to those spots. One is a remarkable mound of gravel, near Fabyan's 

 Tavern, five miles from the notch in the "White Mountains. Its height cannot be 

 less than twenty or thirty feet above the surrounding surface ; and its top (mea- 

 sured with the aneroid barometer) is 1537 feet above the ocean. (See a sketch 

 and description of it in Vol. I of the Transactions of the Association of American 

 Geologists and Naturalists, Plate viii, Fig. 10.) 



The other case presents us with several ridges of sand, nearly straight, in a val- 

 ley lying southwest from Adams' Tavern, in Conway, New Hampshire, towards 

 Eaton. The principal ridge may be a half a mile long, terminated on the north 

 by a pond. These ridges seem to me to differ from those in Andover, in being 

 nearly straight ; but they need further examination. 



4. Deltas and Dunes. 



Connecticut river has, of course, made some delta-like accumulations at its 

 mouth, but they are not extensive, being probably swept away by tides and cur- 

 rents. The same is true of the smaller rivers of New England, but as I have not 

 studied any of these with care, I pass them by. 



The dunes of southeastern Massachusetts have long since been described. They 

 are sometimes quite high and large, requiring vigorous and expensive efforts to 

 arrest their progress. Along the Connecticut valley small ones exist in Hadley, 

 Granby, Montague, and Enfield, Ct., which are slowly advancing southeasterly, in 

 consequence of the predominance of northwesterly winds. These dunes are 

 derived from the sands of one of the higher terraces of the valley. 



