794 REPORT—1899. 
volcanic ashes, and from the débris ejected from submarine volcanoes, together 
with the products of their decomposition. Quartz particles, which play so 
important a 7éle in the Terrigenous Deposits, are almost wholly absent, except 
where the surface waters of the ocean are aflected by floating ice, or where the 
prevailing winds have driven the desert sands far into the oceanic areas. Glau- 
conite is likewise absent from these abysmal regions. The various kinds of Pelagic 
Deposits are named according to their characteristic constituents, Pteropod Oozes, 
Globigerina Oozes, Diatom Oozes, Radiolarian Oozes, and Red Clay. 
The distribution of the deep-sea deposits over the floor of the ocean is shown 
on the map here exhibited, but it must be remembered that there is no sharp line 
of demarcation between them; the Terrigenous pass gradually into the Pelagic 
Deposits, and the varieties of each of these great divisions also pass insensibly 
the one into the other, so that it is often difficult to fix the name of a given 
sample. 
On another map here exhibited the percentage distribution of carbonate of lime 
in the deposits over the floor of the ocean has been represented, the results being 
founded on an extremely large number of analyses. The results are also shown 
in the following table :— 
Sq. Geo. Miles. Percentage. 
Over 75% CaCO, ; ; 6,000,000 58 
50 to 75% =,, . - 24,090,000 23°2 
25to 50% =,, 5 - 14,000,000 13°5 
Under 25% __—s« . - 59,000,000 57°65 
103,000,000 100 
The carbonate of lime shells derived from the surface play a great and puzzling 
réle in all deep-sea deposits, varying in abundance according to the depth of the 
ocean and the temperature of the surface waters. In tropical regions removed 
from land, where the depths are less than 600 fathoms, the carbonate of lime due 
to the remains of these organisms from the surface may rise to 80 or 90 per cent. ; 
with increase of depth, and under the same surface conditions, the percentage of 
carbonate of lime slowly diminishes, till, at depths of about 2,000 fathoms, the 
average percentage falls to about 60, at 2,400 fathoms to about 30, and at about 
2,600 fathoms to about 10, beyond which depth there may be only traces of 
carbonate of lime due to the presence of surface shells, The thin and more delicate 
surface shells first disappear from the deposits, the thicker and denser ones alone 
persist to greater depths, A careful examination of a large number of obser- 
vations shows that the percentage of carbonate of lime in the deposits falls off 
eels more rapidly at depths between 2,200 and 2,500 fathoms than at other 
epths. 
Pthe Red Clay, which occurs in all the deeper stretches of the ocean far from 
land, and covers nearly half of the whole sea-floor, contains—in addition to vol- 
canic débris, clayey matter, the oxides of iron and manganese—numerous remains 
of whales, sharks, and other fishes, together with zeolitic crystals, manganese 
nodules, and minute magnetic spherules, which are believed to have a cosmic 
origin. One haul of a small trawl in the Central Pacific brought to the surface on 
one occasion, from a depth of about two and a half miles, many bushels of 
manganese nodules, along with fifteen hundred sharks’ teeth, over fitty fragments 
of earbones and other bones of whales. Some of these organic remains, such as 
the Carcharodon and Lamna teeth and the bones of the Ziphioid whales, belong 
apparently to extinct species. One or two of these sharks’ teeth, earbones, or 
cosmic spherules, may be occasionally found in a Globigerina Ooze, but their 
occurrence in this or any deposits other than Red Clay is extremely rare. 
Our knowledge of the marine deposits is limited to the superficial layers; asa 
rule the soundir.g-tube does not penetrate more than six or eight inches, but in 
some positions the sounding-tube and dredge have been known to sink fully two feet 
into the deposit. Sometimes a Red Clay is overlaid by a Globigerina Ooze, 
more frequently a Red Clay overlies a Globigerina Ooze, the transition between 
the two layers being either abrupt or gradual. In some positions it is possible to 
