The Oceanic series is generally overlaid directly, and unconformably, by coral limestones; but at Bissex Hill, at the base of the coral limestones, and resting unconformably upon the Oceanic series, there is a Globigerina marl.
Traced landwards the muds become more sandy, while on their outer margins they grade into the abysmal deposits, such as the globigerina ooze (see Ocean And Oceanography).
Pteropod ooze is merely a local variety of globigerina ooze in which the comparatively large but very delicate spindleshaped shells of pteropods happen to abound.
This fact, together with the extraordinarily rare occurrence of such remains and meteoric particles in globigerina ooze, although there is no reason to suppose that at any one time they are unequally distributed over the ocean floor, can only be explained on the assumption that the rate of formation of the epilophic deposits through the accumulation of pelagic shells falling from the surface is rapid enough to bury the slowgathering material which remains uncovered on the spaces where the red clay is forming at an almost infinitely slower rate.
The Globigerina of the chalk--it is unnecessary to speak of them.
The eupelagic deposits are subdivided by Kriimmel into two main groups; (a) epilophic,' including the pteropod, globigerina and diatom oozes occurring on the rises and ridges and in the less deep troughs.
These peculiarities, combined with the striking absence of mineral constituents, distinguish the eupelagic globigerina ooze from the hemipelagic calcareous mud.
The reddish colour comes from the presence of oxides of iron, and particles of manganese also occur in it, especially in the Pacific region, where the colour is more that of chocolate; but when it is mixed with globigerina ooze it is grey.
There is even some hesitation in accepting the continuity of the chalk with the globigerina ooze of the modern ocean.
Just like the Globigerina already known to occur in chalk.