REPORT ON THE DEEP-SEA DEPOSITS. 
201 
AVith reference to the percentage, often rather high, of phosphate of- lime, it must 
be referred to the remains of organisms, such as teeth of fish, bones of Cetaceans, and 
sometimes to small concretions of phosphate of lime, which are met with in some of the 
deposits ; we know from the analyses of clayey matters that phosphates are generally 
present in these substances. The phosphate of lime may also be due to the pseudomorphic 
interchange between carbonate of lime and soluble salts of phosphoric acid. 
Manganese, which is one of the most constant elements in the Eed Olay, is not shown 
in all the quantitative analyses, but the pyrognostic reactions show its presence every- 
where, and it forms in these deposits, along with iron and earthy matters, the ill-defined 
variety known by the name of wad, and is associated with nickel, cobalt, and barium, 
and nearly all the rare metals, as shown by Dr. Gibson’s analyses. We will return to this 
subject when dealing with the manganese nodules and their mode of formation. 
Regarding now the insoluble part of the deposit, it will be seen that here too there 
is an excess of silica. It is not possible to explain this excess by the presence of the 
siliceous remains of organisms, for these do not resist the action of caustic potash. In 
certain cases the presence of quartz must be admitted, for the quantity of bases is not 
sufficiently high, but these grains of quartz do not belong normally to the Red Clay 
which is much more generally due to the decomposition of volcanic materials, in which 
quartz is relatively rare or absent. We have seen that special conditions, such as 
atmospheric currents and glacial phenomena, may serve to account for the presence of 
quartz in certain regions where Red Clays are in process of formation. The microscopic 
examination of the Red Clays has shown the presence in these deposits of orthoclase, 
plagioclase, and bisilicates, which contain variable proportions of lime, magnesia, alumina, 
iron, and manganese ; these substances appear in the analyses as the insoluble portion, 
and must be in the form of anhydrous silicates. The percentage of the alkalies not 
having been determined, and the presence of volcanic glasses, render it impossible to 
estimate the relative abundance of the different minerals. The analyses, however, confirm 
what has been said as to the presence of silicates and silicated rocks in the sediments. 
A second series of analyses,' made according to the methods pointed out on pages 27 
and 28, is tabulated here, the results of which, it will be seen on examination, approach 
those obtained from the preceding analyses. 
station. 
Depth in 
Fathoms. 
No. 
SiO^ 
CO 2 
AI 2 O 3 
Fe. 20 s 
FeO 
MnO .2 
CaO 
MgO 
K 2 O 
Na^O 
H 2 O 
Total. 
9 
3150 
24 
56-89 
20-28 
10-02 
...* 
1-31 
2-56 
1-91 
0-81 
6-7-2 
100-50 
29 
2700 
25 
42-15 
9-8-2 
20-27 
7-06 
13-22 
2-15 
1-12 
0-72 
3-75 
100-26 
281 
2385 
26f 
43-32 
13-96 
17-50 
4-36 
5-96 
5-89 
1-66 
1-74 
6-41 
100-80 
286 
2335 
27 
39-10 
1-50 
15-40 
17-93 
5-75 
8-37 
2-37 
1-27 
1-40 
8-89 
101-98 
* Traces of barium, manganese, and phosphoric acid. t In No. 26 the finer parts had been washed away. 
(deep-sea deposits chall. exp. — 1890.) 26 
