222 
THE KHAETIC BONE BEDS 
as a result, the pebbles would be in larger proportion 
than they were originally. 
Respecting the Coprolites little need be added, except 
to note that their enormous quantity, position, and 
generally uninjured condition provide additional proof 
that the animals lived on the spot, and also furnish another 
“ nail in the coffin ” for the drift theory. 
Origin of the Bone Beds, 
The way is now clear for considering the origin of the 
Bone Beds. 
In the last days of the Triassic Marls we have the spec- 
tacle of a worn-out dying formation, slowly sinking into 
its grave — a desert land, almost totally destitute of life in 
any shape. 
But from the east, or south-east, a remarkable change of 
scene was approaching. Following on the slowly sinking 
land, the waters of the great Rhsetic Sea (which at that 
time probably covered a large proportion of what is now 
Europe) were advancing, not rushing in as a tempestuous 
flood, but slowly and surely encroaching, corresponding 
with the gradual depression of the land ; evidence of this 
is found in the small amount of erosion of the underlying 
rocks, and the absence of large or numerous fragments 
torn off in its progress, the pieces included in the basement 
beds being comparatively small, and not occurring in any 
great quantity. 
In the wake of this Rhaetic Sea came immense shoals 
of fish, mostly of a carnivorous character, and these were 
followed up by numbers of the fierce and voracious “ Sea 
Dragons,” known as Saurians. The struggle for life in 
this multitude would be tremendous, and probably many 
thousands were killed and eaten daily. A fish would be 
caught by a Plesiosaurus, crushed to pieces in his powerful 
