78 On Coral Reefs and Islands. 
widening gradually renders the bank steeper, and the rate of 
increase in width is rapidly diminished. And if the bank were 
not sloping, there is still reason to believe that the patches would 
not attain a great width at the surface, of the sea, owing tot 
goons, or at the bottom of the larger, affords an interesting illus- 
tration of the result produced by a triturating sea, as compa 
with that from more gently agitated waters. The rude seashore 
waves give rise to sand or pebbles; while the gentle undulations 
or ripplings of inland waters produce mud by their finer tritura- 
tion. In the latter case the finely comminuted matter is retained 
beneath the quiet waters, in the former the rude action washes 
it away. 
few rods from waters prolific with the productions of the se 
and were made from them. Mo 
An explanation of this peculiarity, is obvious on the principle 
already discussed—the action of a triturating sea. Everything 
washed towards the shores, is ground down by this action and 
reduced to sand; and a large part of the sand is worn out: 
carried off by the sea; or, being thrown up by the reef, is blow! 
inward by the winds. ee 
It is a natural inference from these facts, that the non-fossilif 
erous sandstones of our continents are no good evidence of the 
absence or sparing diffusion of animal life in the seas about who 
shores they may have been formed. If this destruction of fo 
sils is so complete when the sands are of limestone, much mole 
ce ¥ 
& ina : ge : as 2 sw 
ie 
