WHITE CHALK COMPARED WITH CALCAREOUS OOZE. 
539 
modern ooze, as well as the character of the line surrounding 
matrix, lead irresistibly to the conclusion that we are here dealing 
with an ancient Globigerina ooze. I have washed a sample of 
the chalk from Codrington (Barbados) and find that nine-tenths 
of the Foraminifera are Globigerina, and that in quantity there 
are more than treble the number of all the larger Foraminifera 
that would be obtained from the washing of a piece of chalk taken 
from the middle of the T erebratulina zone. 
“ With respect to the possible solution of Globigerina , my observa¬ 
tions lead me to think that when a calcareous mud originally consist¬ 
ing of amorphous material and fragments of calcareous organisms 
and Foraminifera is undergoing a gradual change toward crystal¬ 
lisation, the coarse particles, such as the shell-fragments and Fora- 
minifera, retain their identity the longest, and that it is only on the 
sea-floor that Foraminifera break up into unrecognisable particles. 
Although percolating water' can and does obliterate the character 
of the minutest particles, the larger calcareous objects retain their 
shape, and even their structure, although they may he surrounded 
by a greatly altered matrix. 
“ Hence, though a secondary crystallisation has been set up in 
the Barbados rocks and in our own chalk after the upheaval of these 
deposits into dry land, yet I do not think this has had any destructive 
effect on the Foraminifera. It seems to me that all those which 
escaped destruction on the ocean-floor have been preserved, and will 
continue to be preserved, unless a further and more complete 
crystallisation of the whole rock should take place. 
“ Assuming, therefore, as we seem justified in doing, that in 
Barbados chalk we have an ancient Globigerina ooze in its massive 
form, as distinct from the surface layer of modern ooze, and that 
this has advanced as far in the process of rock-making as our own 
chalk, it is particularly noteworthy that it still retains the leading 
features of a true Globigerina ooze. Consequently, when we find 
that English chalk closely resembles the Barbadian chalk in most 
respects, but differs in this particular of the dominant organic 
constituent, we may reasonably infer that species of Globigerina did 
not swarm in the sea of the European chalk as they do in the larger 
oceans of the present day, and that our chalk is not truly a 
Globigerina ooze.” 
In this connection we should remember that even at the pre¬ 
sent time there are oceanic areas where Globigerina is not the 
dominant type. This is the case in the “ deep-water cold area ” of 
the northern part of the North Atlantic between Norway, Iceland, 
and Greenland, as described by Professor G. 0. Sars.* Here the 
sea bed, at depths of from 500 to 2,000 fathoms, consists of a soft, 
sticky mud, of which the chief organic constituent is Bilocvlina 
ringens. The deposit has been called “ Biloculina ctey,” but as the 
* See Challenger Reports, Vol. ix., p. 139 (Foraminifera). 
