TEMPEIATURES. 



237 



tions where the current was of less velocity, that we found the 

 greensand deposits, and made ^n occasional successful haul of 

 the trawl or dredge. But the condition of the bottom speci- 



Fig. 165. 



mens and the absence of silt from our hauls gave us every in- 

 dication that the floor of the trough of the Gulf Stream was 

 bare and hard, and practically swept %^ i ,^^ 



clear of all debris, and consequently 

 could afford little foothold for the 

 development of animal life. 



The soundings made by the 

 " Blake " to the northward of San | 

 Domingo (Fig. 164) and to the east- ^ 

 ward of the Bahamas, as far as the 

 Bermudas (Fig. 165), and from the 

 Bermudas again along the triangle 

 bounded by the Bermudas, Cape Hat- 

 teras (Fig. 166), and the southern ' 

 coast of Massachusetts (Fig. 167), 

 have developed the following facts : namely, that there must 

 be a ridge which prevents water colder than 36° from finding 



Fig. 166. 



