22 
COLE : CHALK OF YORKSHIRE. 
to have beeu the primaiy cause of the non-coherence of the layers 
above and below ; sometimes as many as twenty of these partings 
will occur in one or two inches of chalk, dividing it into as 
many thin plates. On the other hand, la3^ers of fuller's earth from 
one to three inches thick are occasionally found, and also beds of 
chalk one or two feet thick, without any parting- at all. 
Where masses of chalk have been rolled about on the sea 
shore and rounded, remarkable wavy lines like the sutures of a 
skull, may be traced on the surface. These are due to extremely 
fine layers of fuller's earth. We call it "fuller's earth" for lack 
of a better word, but it seems to have been a fine sediment of 
mud, deposited over the ocean fioor as the chalk was accumulating, 
representing- a certain amount of denudation carried on by the 
waves, much the same as the lagoons of coral atolls in the Pacific 
receive muddy deposits from the disintegration of the reefs. 
If this idea is correct, it follows that chalk was not deposited 
in a deep sea, as once supposed, but in comparatively shallow 
waters, where coral reefs existed in all dii'ections, with no neigh- 
bouring land, and no rivers bringing down sand and muddy 
impurities to stain the pure whiteness of the chalk. 
This peculiar rock is doubtless composed largely of the 
calcareous skeletons of foraminifera which swarmed in the warm 
waters, which then covered Central Europe, much the same as 
they now contribute to the formation of the grey ooze of the 
Atlantic, but the formation of chalk was probably greatly acceler- 
ated by the disintegration of coral reefs, which, in the form of 
minute calcareous sediment, would assist in the accumulation of 
the beds known as Chalk. 
The chalk area extends, with occasional breaks from Ireland 
to the Crimea, and from Sweden to the Pyrenees. It is absurd 
to suppose that this area ever formed a deep sea. Continents grow 
like everything else, and materials from the land, brought down 
by rivers and carried out to sea, are invariably deposited within 
