312 Deposit of Shells near Borromwstounness. 
in the pools. he upper and under surface of the stratum 
(seen everywhere in section) form lines as straight as if ad- 
justed by levelling, and their position in this respect corre- 
sponds perfectly with that of the adjoining beach, which is 
remarkably smooth and uniform, and declines only at the 
rate of 1 foot in 400. The shells are covered by a bed of 
dark-brown sandy clay, from two to three feet thick, and rest 
on a deposit of the same substance, which closely resembles 
the mud spread over the present beach. They are all of one 
species, the cockle, or Cardium edule, and of various sizes 
down to the most minute. Though mixed with a small por- 
tion of the clay which covers them, they lie so compactly, 
that they present to the eye the appearance of a layer of chalk 
nodules ; and they are seen in myriads on the surface of the 
clay dug out of the pools, and piled up on the space between 
them. Very few of them are fractured, and the two valves 
are generally united. The pools reach within a few yards of 
the high-water line; but the number of broken shells seen 
on the beach shews that the bed had once extended farther 
northward, and that part of it has been cut away by the 
sea. We have here apparently a picture of what passes at 
the bottom of the sea in depths beyond our reach; a colony 
or settlement of the Cardium edule in its native seat, covering 
at least one, but probably several, acres. The bed is at pre- 
sent about the level of high water, or a little above it, while 
the natural abode of the cockle, according to Mr Broderip, is 
from the low-water line to a depth of 13 fathoms. . The con- 
tinuity of the bed, its regular level, its remarkable unifor- 
mity, its composition confined to a single species, and the state 
of the shells, which are generally entire, and have the two 
valves united, shew that they are in their native locality, and 
prove that they could only have been raised to their present 
elevation by an upheaval of the land. This upheaval must 
have been to the extent at least of 18 feet, which is the differ- 
ence betwixt high and low water, but very probably it was 
twice as much ; for evidence of a change of level to the ex- 
tent of 30 or 40 feet is found along both shores of the 
Forth. Inundations of the sea, caused by storms, have been 
called in to account for such deposits, but in my opinion 
very inconsiderately. That a sudden and violent movement 
