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Wallich writes in 1862 "By sinking very fine gauze nets to considerable depths, I have repeatedly satisfied myself that Globigerina does not occur in the superficial strata of the ocean."
Three soundings in 2,050, 1,900, and 1,950 fathoms on the 'Dolphin Rise' gave highly characteristic examples of the Globigerina formation.
One of the commonest is something like a badly-grown raspberry, being formed of a number of nearly globular chambers of different sizes congregated together. It is called Globigerina, and some specimens of chalk consist of little else than Globigerinæ and granules. Let us fix our attention upon the Globigerina. It is the spoor of the game we are tracking.
One of the commonest is something like a badly-grown raspberry, being formed of a number of nearly globular chambers of different sizes congregated together. It is called Globigerina, and some specimens of chalk consist of little else than Globigerinoe and granules. Let us fix our attention upon the Globigerina. It is the spoor of the game we are tracking.
It may be taken as a law that any genus of animals which is found far back in time is capable of living under a great variety of circumstances as regards light, temperature, and pressure. Now, the genus Globigerina is abundantly represented in the cretaceous epoch, and perhaps earlier.
The 'Globigerina' of the Atlantic soundings is identical with that which occurs in the chalk; and the casts of lower silurian 'Foraminifera', which Ehrenberg has recently described, seem to indicate the existence at that remote period of forms singularly like those which now exist.
This soft substance is, in fact, the remains of the creature to which the Globigerina shell, or rather skeleton, owes its existence and which is an animal of the simplest imaginable description.
Passing from the middle plateau of the Atlantic into the western trough, with depths a little over 3,000 fathoms, the red clay returned in all its purity; and our last sounding, in 1,420 fathoms, before reaching Sombrero, restored the Globigerina ooze with its peculiar associated fauna. "This section shows also the wide extension and the vast geological importance of the red clay formation.
The larger Foraminifera are attacked, and instead of being vividly white and delicately sculptured, they become brown and worn, and finally they break up, each according to its fashion; the chamber-walls of Globigerina fall into wedge-shaped pieces, which quickly disappear, and a thick rough crust breaks away from the surface of Orbulina, leaving a thin inner sphere, at first beautifully transparent, but soon becoming opaque and crumbling away.
As I have pointed out elsewhere, it at once became obvious that the calcareous sticky mud of the Atlantic was made up, in the main, of shells of Globigerina and other Foraminifera, identical with those of which the true chalk is composed, and the identity extended even to the presence of those singular bodies, the Coccoliths and Coccospheres, the true nature of which is not yet made out.
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