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 Bank 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 it 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 



^ Another break in the coast line is this hole to have a most remarkable char- 

 thus described by Professor J. E. Hilgard : acter. Its depth varies from one hundred 

 " During the summer of 1882 the ' Blake,' and fifty to over four hundred and fifty 

 under command of Lieutenant - Com- fathoms, the bottom being of mud ; and 

 mander W. H. Brownsou, was engaged in about the centre a knoll of mud, gra- 

 in sounding off the entrance of New York vel, and shell rises up to within sixty-four 

 harbor. The charts have hitherto shown fathoms of the surface. The dividing 

 a spot about a hundred miles south-east ridge between the hole at its deepest 

 of Sandy Hook known as the ' hundred point and the deep water outside has a 

 and forty-five fathom hole.' [Mr. Lin- least depth of one hundred and twenty- 

 denkohl (American Journal of Science, nine fathoms. There seems to be a con- 

 June, 1885, p. 475) has suggested that tinuation of bottom of irregular character, 

 this so-called hole is one of a series of which extends from Sandy Hook about 

 mud holes, showing the existence of an south-east ; for about two hundred miles 

 ancient river channel, and that these holes farther the depth is over three thousand 

 were once a part of a deep ravine, form- fathoms, surrounded by very much shoaler 

 ing the outlet of the river to the ocean.] depths." 

 In her soundings, the ' Blake 'discovered 



