IV. 



TOPOGRAPHY OF THE EASTERN COAST OF THE NORTH AMERICAN 



CONTINENT. 



Only the most general features of the topography of the 

 Western Atlantic, including the Gulf of Mexico and the Ca- 

 ribbean, were known before the explorations of the " Blake." 

 The course of the hundred-fathom line from George's Bank to 

 Cape Hatteras, the Straits of Florida and the Gulf of Mexico, 

 was accurately laid down from the work of the hydrographic 

 parties of the United States Coast Survey. (Fig. 55.) The 

 hundred-fathom line indicates in a general way the true conti- 

 nental outline of the eastern coast of the United States. The 

 continental slope connecting this submarine shelf with the bed 

 of the Atlantic, and with the basins of the Gulf of Mexico and 

 of the Caribbean, was traced in its details by the successive ex- 

 peditions of the " Blake." We must except the oceanic lines 

 run by the " Challenger," connecting Nova Scotia and New 

 York with the Bermudas, and the Bermudas with St. Thomas.^ 



^ " Similar investigations," says Pro- Coast Survey in developing the configu- 

 fessor Hilgard in an account of the work ration of the ocean-bed between the Ber- 

 of the " Blake," " have since been pros- mudas and the West India Islands, and 

 eeuted by Commanders Bartlett and northward to the Banks of Newfound- 

 Biowuson, U. S. N., under the direction land, and in defining the limits of the 

 of the Superintendents of the Coast Sur- continental plateau, which, extending 

 vey, in the western part of the North At- from the coast to the hundred-fathom 

 lantic, — that great embayment, which, line, may be described as the western rim 

 limited by Newfoundland on the north of this great basin of the North Atlantic. 

 and by the Windward Islands on the . . . During the winter of 1881 to 1882 

 south, might be not inaptly named the the 'Blake' was engaged in developing 

 Gulf of North America. The depths and the limit and general character of the 

 temperatures obtained by these officers, great Atlantic basin between the Bermu- 

 upon lines run across the course of the das and the Bahamas, and along the out- 

 Gulf Stream, and connecting with those side of the West India Islands as far to 

 run by H. M. S. * Challenger ' in 1873, the eastward as St. Thomas. This cruise 

 will make apparent the part taken by the has been of great interest. The bed of 



