isfactorily accounting for its mode of formation and origin.
By the researches of Carpenter, Wyville Thomson,
Huxley, Wallich, and others, it has, however, been shown
that there is now forming, in the profound depths of our
great oceans, a deposit which is in all essential respects
identical with chalk, and which is
generally known as the "Atlantic ooze," from its having been
first discovered in that sea. This ooze is found at great
depths (5000 to over 15,000 feet) in both the Atlantic and
Pacific, covering enormously large areas of the sea-bottom,
and it presents itself as a whitish-brown, sticky, impalpable mud,
very like greyish chalk when dried. Chemical examination
shows that the ooze is composed almost wholly of carbonate of
lime, and microscopical examination proves it to be of organic
origin, and to be made up of the remains of living beings.
The principal forms of these belong to the _Foraminifera_, and
the commonest of these are the irregularly-chambered shells of
_Globigerina_, absolutely indistinguishable from the
_Globigerinoe_ which are so largely present in the chalk (fig. 8).
Along with these occur fragments of the skeletons of other larger
creatures, and a certain proportion of the flinty cases of minute
animal and vegetable organisms (_Polycystina_ and _Diatoms_).
Though many of the minute animals, the hard parts of which form
the ooze, undoubtedly live at or near the surface of the sea,
others, probably, really live near the bottom; and the ooze
itself forms a congenial home for numerous sponges, sea-lilies,
and other marine animals which flourish at great
depths in the sea. There is thus established an intimate
and most interesting parallelism between the chalk and
the ooze of modern oceans. Both are formed essentially in
the same way, and the latter only requires consolidation to
become actually converted into chalk. Both are fundamentally
organic deposits, apparently requiring a great depth of water
for their accumulation, and mainly composed of the remains of
_Foraminifera_, together with the entire or broken skeletons
of other marine animals of greater dimensions. It is to be
remembered, however, that the ooze, though strictly
representative of the chalk, cannot be said in any proper sense
to be actually _identical_ with the formation so called by
geologists. A great lapse of time separates the two, and though
composed of the remains of representative classes or groups of
animals, it is onl