IV DEPTHS AND DEPOSITS OF THE OCEAN 201 



of a dark brown colour which proved to be Red clay, with only 

 25 per cent of calcium carbonate, though the mass of the sample 

 was a Globigerina ooze with 64 per cent of calcium carbonate. 

 At Station 100, in 835 fathoms, the sounding-tube brought up a 

 section about nine inches in length, which was extremely interest- 

 ing because of the great difference between the upper and lower 

 portions, the upper portion, to the extent of three or four inches, 

 being a Globigerina ooze with 58 per cent of calcium carbonate, 

 while the lower portion was a Blue mud with only 26 per cent 

 of calcium carbonate. At Station 88, in 1703 fathoms, the 

 sounding-tube brought up a section about fourteen inches in 

 length, which showed little difference to the naked eye, although 

 the colour was darker in the lower portion, the upper portion 

 being rather lighter in colour, less coherent, and more granular ; 

 the deposit was a Globigerina ooze, containing 83.79 per cent of 

 calcium carbonate in the upper portion, 73.66 per cent of calcium 

 carbonate in the middle portion, and 62.1 per cent of calcium 

 carbonate in the lower portion. It is curious that at this 

 station the trawl brought up a large quantity of empty pteropod 

 shells (chiefly Cavolinia trispinosa), while in the samples from 

 the soundjng-tube submitted to examination no pteropods were 

 observed. It is possible that the trawl may have worked 

 over shallower depths than where the sounding was taken. 

 Similarly, at Station 23, where the depth was 664 fathoms, the 

 Petersen net sent down with 820 fathoms of line and towed 

 throughout the night of 5th and 6th May brought up a large 

 amount of empty pteropod shells (principally Cavolinia inflexa) ; 

 indeed, the pteropod shells at this station differ strikingly 

 in general appearance from those taken at Station 88, ten 

 degrees farther north. At Station 34, in 1185 fathoms, the 

 middle portion of the section from the sounding-tube, about six 

 inches below the upper surface, showed dark-coloured patches 

 containing a large proportion of volcanic glass splinters, to 

 which the dark colour was due ; the volcanic glass was quite 

 fresh and unaltered, as though the products of a volcanic eruption 

 (probably submarine, since the glassy fragments showed no trace 

 of friction or decomposition but were perfectly angular) had 

 been overlain by new material to the depth of six inches. 



We append the detailed description of a typical Globigerina 

 ooze taken by the " Michael Sars " to the south of the Azores: — 



"Michael Sars" Station 55. loth June 1910. Lat. 36° 24' N., 

 long. 29° 52' W. ; depth, 3239 m. (1768 fathoms). 



