i894- 
251 [Shaler. 
Moreover the interior margin of the sea-wall is generally covered 
by an extensive system of low dunes which were evidently slowly 
accumulated. These dunes have their characteristic topography 
which would have been effaced by any vigorous incursion of the 
sea. 
Although I regard the evidence afforded by the coast-line south 
of New York ns less determinative than that obtained in New 
England, it seems to me eminently probable that the whole coast 
of the United States from Eastport to Cape Florida has been for 
a considerable period, perhaps for ten thousand years or more, 
exempt from the action of any great marine waves formed by 
earthquakes. My observations on the shore lands of Nova Scotia 
and Cape Breton, though less carefully made, incline me to make 
the same statement concerning that region. Similar though less 
connected observations on the western sliores of Great Britain 
and northern France lead me in a general way to the same con- 
clusions. They are to the effect that the North Atlantic has been 
exempt from this class of cataclysms since its lands came to their 
present attitudes with reference to the sea. 
It ai)pears to me desirable to extend this system of observations 
to other portions of the ocean border. To accomplish this task, 
the observer should first make himself acquainted with the facts as 
exhibited along our New England coast. He should then study 
the part of South American shore which has been most subject to 
these inundations. A cai-eful comparison of the topographic 
details in these two sections would carry the inquiry to its con- 
clusion. 
I now turn to the evidence concerning the violence of earth- 
quake shocks as indicated by topographic monuments on the land 
areas. The (Question we have hitherto considered does not concern 
the energy of the shocks at the point where they occur beneath 
the sea, of which we can have no evidence, but the effect of the 
waves propagated through the sea for great distances by the 
seismic impulse. Hereafter our question will be as to the energy 
of the movement in the earth itself as indicated by the details of 
the surface. As a preparation for this inquiry I have carefully 
observed the topographic features in the part of Italy where 
earthquakes of great violence frequently occur. I have en- 
deavored to apply the considerations derived from such study 
in regions of great seismic activity to other districts in which 
