258 ELEMENTARY GEOLOGY 
Foramenifera, nearly microscopic creatures belonging 
to the genus Globigerina, are the most common in this 
deposit, which is then called Globigerina ooze (Fig. 
146). Since almost every bit of this fine-grained mud 
represents the life and death of a minute animal, one 
may easily see that it is a 
deposit whose growth is 
extremely slow. In addition 
to the Globigerina, there are 
other organic remains, to- 
gether with bits of pumice. 
Sometimes the ooze contains 
more of other species than of 
Globigerina, and it is then 
named according to the pre- 
dominant type of animal 
(diatomaceous ooze, pteropod 
ooze, etc.). 
Fig. 146. How long this immense bed 
Globigerina ooze, enlarged by the of ooze has been gathering, 
microscope. 
and how great is its depth, 
cannot be stated; but dredgings in the ocean prove 
it to be one of the most widespread deposits on the 
surface of the earth. Beds of chalk were apparently 
formed m the deep sea away from the neighborhood 
of large land areas, very much in the same manner 
that Globigerina ooze is gathering to-day (Fig. 147). 
