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171 
Black Rock Islets are the foundations of such vanished 
drumlins. 
It is obvious to the most casual observation not only that 
the present shore is strongly marked in all its various features, 
but also that its level has been unchanged for a long time. 
'l'his is seen especially in the essentially finished state of the 
salt marshes, which, over broad and continuous areas, have 
clearly attained their maximum elevation —extreme high tide ; 
and in the great breadth of Nantasket Beach. The front of the 
beach, when it was first established, probably formed a series 
of rather strongly concave curves connecting the drumlins, all 
of which were then fully exposed to the surf. The over-wash 
of the beach at this time formed what is now its rather low and 
marshy inner margin ; while through the additions made by 
the erosion of the drumlins the line of the beach has been 
gradually straightened and advanced seaward until Strawberry 
Hill and the drumlins south of it, although their 'sea-cliffs are 
still sharply defined, are separated and protected from the 
breakers by a wide belt of sand and shingle. The Point 
Allerton drumlins are still within reach of the waves. The 
little hill would probably have been completely swept away 
by this time but for the massive sea-wall which has been built 
around it. Its present area is less than two acres, but it 
probably extended once as far as the beacon and had an esti- 
mated area of forty-five acres—as large as Boston Common. 
Between 1847 and 1860 its cliff receded 65 feet, equal to the 
loss of half an aere. The great hill has lost an estimated area 
of fifteen acres, but the outward growth of the beach has now 
nearly stopped the erosion. The finer material washed from 
the north side of Telegraph Hill has been carried to the west- 
ward to build Windmill Point, which is a miniature Cape Cod. 
In like manner the waste of Green Hill, and possibly of other 
drumlins which once existed in that vicinity, has formed the 
barrier beaches between Strait’s Pond and the Atlantic; and 
even the widest of these, Crescent Beach, is still so narrow that 
