[109] FISHERIES OF THE UNITED STATES. 621 



351, and 640 fathoms, fragments and nodular masses, or concretions, of 

 a peculiar calcareous rock, evidently of deep-sea origin, and doubtless 

 formed at or near the places where it was obtained. These specimens 

 varied in size from a few inches in diameter up to one irregular nodular 

 mass, taken at station 1124, in 640 fathoms, which was 29 inches long, 

 14 broad, and 6 thick, with all parts well rounded. This probably 

 weighed 60 pounds or more. The masses differ much in appearance, 

 color, texture, and fineness of grain, but they are all composed of grains 

 of siliceous sand, often very fine, cemented by more or less abundant 

 calcareous matter. The sand consists mainly of rounded grains of quartz, 

 with some feldspar, mica, garnet, and magnetite. It is like the loose 

 sand dredged from the bottom in the same region. The calcareous ce- 

 menting material seems to have been derived mainly from the shells of 

 foraminifera in the same region. In some cases I was able to identify 

 distinct casts of foraminifera, and in some pieces of rock distinct fossil 

 shells were found, apparently of recent species. It is probable that 

 these rocks belong to a part of the same formation as has been previ- 

 ously recorded from the fishing banks farther east. No rocks of this 

 kind are found on the dry land of this coast." 



