152 
THE VOYAGE OF H.M.S. CHALLENGER. 
The mineral particles increased in size and number as the American continent was 
approached, where they consisted of fragments of quartz, monoclinic and triclinic felspars, 
hornblende, augite, magnetite, mica, and glauconite. An ideal section, with depths and 
percentages of carbonate of lime, is given in Diagram 2. On the 7th May a large block 
of syenite weighing 490 lbs. (222 kilogrammes), which had become jammed between the 
arms of the dredge, was brought up from 1340 fathoms. In this and the other dredgings 
within the iiiHuence of the Labrador current, over 100 miles from the shore, many stones 
were dredged, most of them being rounded pebbles or large grains with rounded angles ; 
nearly two-thirds of the smaller fragments were milky quartz, w^hilst the larger fragments 
were quartzite, compact limestone, dolomite, mica-schist, and serpentine rocks, some of 
them with glacial striations. These deposits along the American coast were Blue Muds 
with a redtlish surface layer, in which quartz and fragments of ancient rocks were abun- 
dant, making up from 40 to 70 per cent, of the deposits in 1240, 1350, and 1340 fathoms, 
while these minerals were not detected in the deposits around Bermuda. 
Halifax to Bermuda . — The deposits from Halifax southwards to Bermuda (see 
Chart 9) were Blue Muds containing from 16 to 32 per cent, of carbonate of lime. The 
larger pelagic Foraminifera and Rhabdoliths became more abundant as Bermuda was 
approached, while the siliceous organisms became fewer. The mineral particles were of 
the same nature as those in the deposits in the previous section, being larger and more 
abundant in the more northern stations which are under the influence of the Labrador 
current. 
Bermuda to the Azores . — With the exception of the deposit from Station 67, 2700 
fathoms, which contained 54 per cent, of carbonate of lime, all the deposits in the section 
between Bermuda and the Azores (see Chart 6) from depths greater than 2400 fathoms 
contained less, and all from depths less than 2400 fathoms contained more, than 50 per 
cent, of carbonate of lime. In the greatest depths, 2850 and 2875 fathoms, there were 
only 8 and 10 per cent. The highest percentage of carbonate of lime was 83'31 in 
1675 fathoms. In the greater depths the carbonate of lime consisted chiefly of fragments 
of pelagic Foraminifera and Coccoliths ; in depths less than 1600 fathoms, the shells of 
pelagic Mollu.scs and fragments of Echinoderms were more or less abundant, and along 
with pelagic and other Foraminifera made up the principal part of the carbonate of lime 
in the deposits. Radiolaria and Sponge spicules never made up more than 1 or 2 per 
«;eut. of the deposit. 
In the deep water immediately to the south of the banks of Newfoundland, there 
were fragments of quartz, monoclinic and triclinic felspars, and fragments of mica-schist 
and other ancient continental rocks. These were believed to be ice-borne fragments, 
although apj)arently south of the soutliern limit of the ice region in the North Atlantic 
as shown on the charts. On approaching the Azores these fragments disappeared more 
or less completely from the bottom, and the mineral particles then consisted almost 
