REPORT ON THE DEEP-SEA DEPOSITS. 
409 
alkalies, especially of potash, and mixed with iron and manganese. The waters may 
deposit the elements thus taken up from the rocks upon the immediate borders of the 
points from which they have been extracted, or they may be carried further away, 
according as the liquid is at rest or in more or less rapid motion. 
We will now show that phenomena analogous to these take place at the bottom of 
the Pacific ; the differences observed are non-essential, and are explicable when the 
location and special conditions are taken into account. Eemembering the nature of the 
rocks found to be present on the bottom in the central regions of the great ocean basins, 
we would expect to observe there the formation of zeolites bearing characters depending 
upon the medium in which they have been developed ; they would be found, not only in 
the vesicles of the volcanic fragments in the form of definite crystallographic individuals 
or in aggregates, but also in a free state, and not enclosed. The sea-water acting upon 
basaltic volcanic material will be charged with elements to be afterwards deposited as 
zeolites, the residue being transformed into an argillaceous mass, in which manganese 
and iron are concreted in nodules of hydrated peroxide. In this argillaceous ooze the 
zeolitic crystals will be deposited, granted that the movement of the water is almost 
insensible ; the solutions could not be carried very far, as is often the case in clays 
derived from the decomposition of subaerial basalts. These crystals cannot be placed in 
positions similar to those upon the solid partitions of crystalline rocks, hence their 
special characteristics ; they are terminated on all sides by crystalline faces or form 
aggregates and spherolithic globules, the surfaces of which bristle with facets. These 
are, indeed, the peculiar characteristics of crystals formed in muddy matters, viz., the 
crystals of gypsum and the radiate groups of sulphide of iron formed under conditions 
fundamentally resembling those under which these microscopic crystals of phillipsite are 
found. Thus the presence of eruptive materials whose decomposition under the action 
of water gives origin to zeolites, the co-existence of these with the normal residue of the 
alteration of basaltic rocks — clay and ferro-manganiferous concretions, the special charac- 
ters of these zeolitic microliths, indeed the whole range of facts observed on the bed of 
the Pacific, contribute to the support of the interpretation here proposed, which appears 
to give an adequate explanation of the origin of these crystals of phillipsite. 
Some points upon which we have not insisted may, however, be raised against the 
view here adopted, and in terminating this discussion we may examine some doubts that 
naturally enough present themselves. It may be asked, in the first place, whether the 
substances extracted by sea-water from silicates of volcanic rocks ought not to be spread 
by diffusion throughout the oceanic mass and be lost in this immense reservoir. To 
remove this objection, it will be sufficient to recall a fact placed beyond doubt by recent 
oceanographical researches, viz., that in great depths the water is not subjected in a 
sensible manner to the influence of superficial movements — waves, tides, and currents — 
but that there is only a massive movement of extreme slowness, in striking contrast 
(deep-sea deposits chall. exp. — 1891 .) 52 
