How Chalk is Made 



lessen ; but in tropical regions, and in warm 

 ocean-streams their numbers are legion. Yet, 

 from depths beyond about two miles, the ooze 

 was not brought up. 



One explanation can be given ; and it is that 

 of the strong dissolving power of sea-water. 

 After a depth of about two miles, the delicate 

 little shells fail to resist that power. Once at the 

 bottom, they might be covered up and pre- 

 served ; but they cease to exist en route thither. 



So in this as in many other instances, we see 

 opposite forces at work. The one force is per- 

 petually undoing what the other force is perpetu- 

 ally doing. Innumerable multitudes of living 

 creatures are at work, taking lime from the 

 water, and constructing carbonate-of-lime. But 

 the ocean is ever seeking to re-dissolve that 

 carbonate-of-lime. 



Another difficult question as to the ooze was 

 whether the shells of which it is mainly made 

 were those of Foraminifera living in the deep 

 sea, far down below the surface, or of Fora- 

 minifera living near the surface. Able men took 

 both sides of the discussion, some ascribing the 

 ooze entirely to deep-sea jelly-specks, others 

 ascribing it entirely to surface jelly-specks. 



The question cannot be said yet to have met 

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