TOPOGRAPHY OF THE EASTERN COAST. 95 
continental shelf increases gradually in width from fifteen miles 
at Cape Hatteras to about one hundred miles off the southern 
coast of New England; opposite the Gulf of Maine the south- 
ern edge of George's Bank is nearly two hundred miles from the 
coast of Maine. In the latitude of Cape Cod and nearly south 
of Cape Sable there is a wide break in the hundred-fathom line, 
giving access to a tongue of the ocean which, in some places, 
extends to within fifteen or twenty miles of the coast of Massa- 
chusetts and Maine. A similar break, the opening into the 
Gulf of St. Lawrence, occurs between Sable Island Bank and 
the Newfoundland banks. 
Between Cape Hatteras and the Bahamas there extends a 
huge triangular plateau, sloping gradually from the shore to 
about the six-hundred-fathom line, where a steeper slope con- 
nects it with the floor of the ocean. As will be seen from the 
map, the thousand-fathom line runs parallel to the hundred- 
fathom line from the eastern extremity of George's Dank to 
Cape Hatteras, and is nowhere more than fifteen miles dis- 
tant from the former. The slope to the two-thousand-fathom 
line, however, is by no means so abrupt, except a little south 
of Hatteras, where 16 is only about fifteen miles distant. It 
varies from forty miles off the extremity of George's Bank to 
over a hundred miles in the normal to the Jersey coast. 
On the southern New England coast the continental shelf 
1 Another break in the coast line is this hole to have a most remarkable char- 
acter, 
thus described by Professor J. E. Hilgard : 
* During the summer of 1882 the * Blake,’ 
under command of Lieutenant - Com- 
mander W. H. Brownson, was engaged 
in sounding off the entrance of New York 
harbor. The charts have hitherto shown 
a spot about a hundred miles south-east 
of Sandy Hook known as the ‘hundred 
[Mr. Lin- 
denkohl (American Journal of Science, 
June, 1885, p. 475) has suggested that 
this so-called hole is one of a series of 
and forty-five fathom hole.’ 
mud holes, showing the existence of an 
ancient river channel, and that these holes 
were once apart of a deep ravine, form- 
ing the outlet of the river to the ocean. ] 
In her soundings, the * Blake" discovered 
Its depth varies from one hundred 
and fifty to over four hundred and fifty 
fathoms, the bottom being of mud; and 
in about the centre a knoll of mud, gra- 
vel, and shell rises up to within sixty-four 
fathoms of the surface. The dividing 
ridge between the hole at its deepest 
point and the deep water outside has a 
least depth of one hundred and twenty- 
nine fathoms. ‘There seems to be a con- 
tinuation of bottom of irregular character, 
which extends from Sandy Hook about 
south-east ; for about two hundred miles 
farther the depth is over three thousand 
fathoms, surrounded by very much shoaler 
, 
depths.’ 
