132 PEBBLES OF THE SEA AND RIVERS. 
accumulated in our rivers and on the sea coasts, 
because, although circumstances were in operation 
anterior to the Deluge which would occasion the 
formation of the same pebbles as we now find, yet, 
they are unequivocally illustrative of the power 
exerted on stone by the violence of river water in its 
rapid descent over mountainous tracts, and of the 
still greater violence with which the waves smooth- 
en the masses of rock which through them have been 
severed from the beds to which they respectively 
belong. No kind of rock seems proof against the 
disintergating agency of propelled water ; the beds 
of our rivers and the beaches of our neighbouring 
sea are Strewed with a profusion of rounded frag- 
ments of every species of stratum of which the 
county boasts. Pebbles of granite, schorl, and 
various sorts of trapp are carried from the central 
districts of the county onwards by slow movements 
to the estuaries, huge granitic blocks are slowly 
undermined as they repose in their beds, and are 
eventually during some winter flood conducted into 
the body of the stream, where they serve greatly to 
restrain the impetuosity of the current, and in con- 
sequence its devastating influences on exposed 
land. During those periods when such extraordi- 
nary elevations of our rivers occur from heavy falls 
of rain or overflowing of springs in the moorland 
districts, the pebbles may be heard striking against 
each other in their progress with the torrent, the 
larger blocks of moorstone, limestone, and trapp 
are also gradually hurled forwards, and in the hurry 
of the streams on these occasions they not unfre- 
quently force new passages in soils readily removed. 
In the moor itself, the stones and blocks lying in 
the beds of the streams are greatly rounded, proving 
the rapidity and violence of the descent of their 
waters during heavy rains and sudden risings of 
