[3] THE BOTTOM OF THE GULF STREAM. 1047 



aud eight stations, in 104 to 435 fathoms, in 1881. These dredgings 

 show the direct southward continuation of the inshore cold belt and 

 the warm belt outside of it, as well as the cold deep-water belt, with 

 but little change in the fauna of each. 



At most of the localities that we have examined the temperature of the 

 water, both at the bottom and surface, was taken, as well as that of the 

 air. In many cases series of temperatures, at various depths, were also 

 taken. Many other physical observations have also been made and re- 

 corded. Lists of the animals from each haul have been made with care 

 and arranged in tables, so far as the species have been determined, up 

 to date. Lists of the fauna will soon be published in these reports. 



South of New England the bottom slopes very gradually from the 

 shore to near the 100-fathom line, which is situated from 80 to 100 miles 

 from the mainland. This broad, shallow belt forms, therefore, a nearly 

 level submarine i)lateau, with a gentle slope seaward. Beyond the 100- 

 fathom line the bottom descends rapidly to more than 1,200 fathoms, into 

 the great ocean basin, thus forming a rapidly-sloping bank, usually as 

 steep as the side of a great mountain chain and about as high as Mount 

 Washington, New Hampshire. This we call the "Gulf Stream Slope," 

 because it underlies the inner portion of the Gulf Stream all along our 

 coast, from Cape Hatteras to Nova Scotia (Plate II). In our explorations 

 a change of locality of less than 10 miles, transverse to the Slope, would 

 sometimes make a difference of more than 3,500 feet in depth. 



Fai ther from the coast the depth continues to increase, but much 

 more gradually, until the depth of about 3,000 lathoms is reached. The 

 Albatross, in 1883, dredged in these deeper waters down to 2,949 fath- 

 oms, in N. lat. 37° 12' 20", W. long. 09° 39', station 2099. 



INFLUENCE OF THE GULF STREAM. 



The bottom along the upper part of this slope and the outermost por- 

 tion of the adjacent plateau, in 65 to 150 fathoms, and sometimes to 200 

 fathoms or more, is bathed by the waters of the Gulf Stream. Conse- 

 quently the temperature of the bottom-water along this belt is decidedly 

 higher than it is along the shallower part of the plateau nearer the 

 shore, in 25 to 60 fathoms. The Gulf Stream itself is usually limited in 

 depth to about 150 fathoms, and often even less, in this region; below 

 this the temperature steadily decreases to the bottom of the ocean basin, 

 where it is about 38°, in 1,000 to 1,400 fathoms. We may, therefore, 

 properly call the ur>per part of the Slope, in about 65 to 150 fathoms, 

 the "warm belt." According to our observations, the bottom tempera- 

 ture of the warmer part of this belt, in 65 to 125 fathoms, is usually be- 

 tween 47° F. and 53° F., in summer and autumn. Between 150 and 200 

 fathoms, the temperatures, though variable, are usually high enough 

 to show more or less influence from the Gulf Stream. On the warm 

 belt we took numerous kinds of animals that were previously known 



