Shalcr.! 250 [March?, 
|>1ut'u- .•u-tioii, an iiis|)rc'lioii of miiiierous cross se<^;tions has 
shown nie thai tlic material wliich tills tlie basins is invariably 
fine sand wliich has been gradually accumulated and not of a 
nature which we should find if it had been brought into its 
position by the tumultuous action of a great invading wave. It 
is not too much to say that any one wave such as has ravaged 
parts of the Pacific shore would have left an ineffaceable mark 
on this delicate topography. I therefore conclude that, since the 
New England coast assumed its present level sometime after the 
close of the glacial period, the region of the North Atlantic 
between America and Europe has been exempt from shocks 
having the magnitude of those which have prevailed in parts of 
the Pacific Ocean as well as in the more southern parts of the 
Atlantic. 
South of New Jersey and thence to southern Florida the evi- 
dence is of a less distinct nature but to the same effect as that 
which we find in New England. The southern sand-plain from 
New Jersey to Cape Florida exhibits gentle undulations appar- 
ently of the same type, though less accented, as is shown in the 
kame terraces of New England ; but these reliefs are so slight, 
rarely exceeding 10 ft. in a square mile, that we cannot make quite 
sure that they have not been subject to the inundations caused by 
earthquakes. There is, however, another feature of this district, 
viz., the barrier beaches of sand, wliich throws some light on our 
problem. From Cape Henry at the mouth of the Chesapeake 
southwardly to Cape Florida, there is an almost continuous barrier 
of wave-tossed sand more or less crowned and backed by dunes. 
This beach wall incloses a series of lagoons so nearly connected 
that in the wet season a canoe can, with a few trifling portages, 
be taken along the length of this extended shore. As may well 
be imagined, this feature affords us certain tests as to the invasion 
of great earthquake waves. An inundation of this nature sweep- 
in<»- over a sand barrier would in good i)art efface it. The lagoons 
behind the barrier su<ldenly filled with water would on the sur- 
gence of the waves burst through the barrier in their escape to 
the sea. Although such openings would inevitably in a short 
time be closed by the movements of the sands, the evidence of the 
former existence of the inlet would be plainly manifest for some 
thousand years. I have examined a good many hundred miles of 
these barricaded waters and find no evidence of such accidents. 
