224 
Geology of Sydney. 
taken as a type of oceanic deposit. In the same class 
must be placed the nummulitic limestone, which 
spreads through Europe, Asia, and Africa, and the 
fusulina limestone which extends from Russia to 
Fra, 63. Silurian Slates, showing how the same beds are repeated in 
a section, by folding. The broken lines above show the 
country removed by denudation. 
Japan. It may be stated here that an oceanic lime- 
stone is not necessarily deposited in very deep water ; 
the only essential condition seems to be that the rock 
should accumulate in a region beyond the influence of 
Fig. 64. — Figure showing slaty cleavage crossing, and also coin- 
ciding with the planes of bedding. 
the sediments which are brought down from the land. 
A shell-bed cemented into stone is another example of 
an organically formed rock. It will be seen, on turn- 
ing to page 72, that rocks of aqueous origin are divided 
