270 THREE CRUISES OF THE " BLAKE." 



The explorations of the " Blake " have extended our know- 

 ledge of the bottom deposits of our coasts so as to include the 

 Gulf of Mexico and the Caribbean. Within the Caribbean, the 

 explorations of the " Blake " have been supplemented by those 

 of the '^ Albatross." In addition to the soundino-s of the 

 " Blake " on the eastern edge of the Gulf Stream, and in the 

 basin of the western Atlantic between the West India Islands, 

 Bermudas, and New York, we have a few observations made by 

 the " Challenger." The work of the " Blake " on the south- 

 ern coast of New England has been materially advanced by the 

 continuous explorations of the United States Fish Commission 

 during the past years. 



From these different sources we may obtain a moderately 

 complete sketch of the character of the bottom deposits of the 

 western Atlantic, and of the adjoining enclosed seas. For the 

 sake of convenience, we shall describe in order the deposits pro- 

 cured from the Gulf of Maine, and from the eastern coast as far 

 south as Cape Hatteras ; next, the specimens from the coast 

 south of Hatteras, to latitude 31° 48^ N., off the northern ex- 

 tremity of the Bahamas ; then those of the Gulf of Mexico, 

 of the Caribbean, and of the West India Islands, closing with 

 the description of the deposits of the basin of the western At- 

 lantic. I shall transcribe descriptions from Mr. Murray's report 

 on the deposits collected by the " Blake," adding observations 

 of general interest from the soundings of Pourtales and of 

 the Fish Commission, and from my own. 



" The deposits procured in the Gulf of Maine, and along- the east 

 coast of the United States as far south as Cape Hatteras, consist of 

 blue or gray colored muds and sands.^ The muds are darker-colored 

 when wet, earthy, plastic, more or less granular, and coherent, drying 

 into hard lumps. These deposits are chiefly made up of the debris of 

 the land of the North American continent. 



" In 1,240 fathoms and Lat. 38° 34' N., off the coast of New Eng- 

 land, the ' Challenger ' dredged many rounded and angular pebbles of 

 milky and hyaline quartz, fine-grained quartzites, feldspathic quartz- 



^ The sandy deposits are found only examined by the " Blake " along our east- 



within 100 fathoms. They lie between ern coast are 1,394 and 1,186 fathoms, 



the coast and the inner edge of the Gulf which are situated between thirty and 



Stream. The greatest depths of the tract forty miles outside the 100-fathom line. 



