DEPOSITS NEAR SEA SHORES. 121 
of which a well known example occurs in the 
oolitic slate of Stonesfield, near Oxford. At 
this place a single bed of calcareous and sandy 
slate not six feet thick, contains an admixture of 
terrestrial animals and plants with shells that 
are decidedly marine ; the bones of Didelphys, 
Megalosaurus, and Pterodactyle are so mixed 
with Ammonites, Nautili, and Belemnites, and 
many other species of marine shells, that there 
can be little doubt that this formation was depo- 
sited at the bottom of a sea not far distant from 
some ancient shore. We may account for the 
presence of remains of terrestrial animals in such 
a situation by supposing their carcases to have 
been floated from land at no great distance from 
their place of submarine interment. 
A similar explanation may be given of the 
mixture of the bones of large terrestrial mam- 
malia with marine shells, in the Miocene Tertiary 
formations of Touraine, and in the Crag of 
Norfolk. 
Cases of Animals clestroijed suddenly. 
The cases hitherto examined, are examples of 
the processes of slow and gradual accumulations 
in which are preserved the remains of marine, 
lacustrine, and terrestrial animals that perished 
during extended periods of time, by natural 
death. It remains to state that other causes 
seem to have operated occasionally, and at 
distant intervals, to produce a rapid accumu- 
