GLACIAL DRIFT. 311 
standing upon the first. Another example may be seen at the south 
end of Long island. It is possible that Steamboat island and its cul- 
mination south in a ridge in shallow water is to be regarded as one of 
these ramparts. 
Sea WALLS. 
A variety of the sea-beach action is indicated by the term sea walls, 
which I suggested for them in 1861.* It is along embankment of smooth 
boulders, without sand or gravel, lying just behind the beaches. When 
the more powerful storms prevail off the coast, stones up to two feet 
in diameter are carried a distance of hundreds of feet, and deposited just 
back of the beaches. Sometimes they are fifteen feet in height. I have. 
noticed them in Rye. 
DisTURBANCES IN MopIFIED DRIFT. 
A few examples of curvature in layers of gravel and sand have been 
noticed. One of them is represented in Fig. 63. It is seen on the east 
Fig. 63.—SECTION IN GRAVEL, WHITEFIELD. 
side of John’s river, in Whitefield, just east of the depot. Coarse gravel 
occupies the centre and lowest part of the arch, and there is another 
mass of it upon the steep slope to the left. The bank was exposed for 
about fifteen feet. 
* Preliminary Report Geology of Maine, p. 270. 
