OCEAN DEPOSITS: GLOBIGERIN A-OOZE 31 



greyish or whitish mud, made up chiefly of coral 

 detritus. But in the neighbourhood of most of 

 the continents we should find — as all round the 

 boundaries of the Bay of Bengal — a fringe or steep 

 "shoot" of dark - coloured mud, and the breadth of 

 this fringe would vary, according to the number and 

 volume of the rivers in the vicinity, from 60 to 

 300 miles. 



To resume our imaginary journey from Madras to 

 the Andamans. At a distance of about 150 miles from 

 shore the mud would begin to change : it would gradu- 

 ally become more and more gritty, and lighter and 

 lighter in colour, until we should at last find ourselves 

 walking on ground something like dirty chalk. This 

 is the Globigerina-ooze that forms such a large part 

 of the bed of the ocean in tropical and temperate 

 regions. 



Globigerina-ooze — so called from the species most 

 constantly and most abundantly found in it — is, for 

 the most part, made up of myriads of dead shells of 

 the minute and lowly animalcules known as Fora- 

 minifera. They belong to the very lowest class of 

 the animal kingdom, and they swarm throughout the 

 warmer seas ; and as they die, their shells, which 

 usually but not always are made of carbonate of lime, 

 fall to the bottom — like, as has been aptly said, a 

 perpetual shower of rain — and there accumulate, to form 

 vast beds of sediment not very different from the 



