1872.] Geology of the Straits of Dover. 223 
below the bottom of the sea; yet it is only in exceptional 
cases that an extra quantity of water is met with in such 
workings; often, indeed, the workings are drier beneath 
the sea than beneath the land. Faults, too, are cut in the 
coal-workings beneath the sea, as beneath the land; but 
these give no more trouble and yield no more water in the 
one case than in the other. The same fault is frequently 
cut several times in parallel lines of workings. 
To sum up the main geological points of this paper :— 
We have seen that the Chalk, the Gault, and the Folkestone 
Beds, have the same charaé¢ters on both shores of the 
Channel, and that they may fairly be assumed to pass 
evenly across the bed of the Channel. The beds below 
the Folkestone Beds differ on opposite sides of the Channel, 
and we have no means of telling how these various beds run 
beneath the Channel, nor their probable thickness at different 
oints. 
: Any tunnel driven through beds lower than the Folkestone 
Beds would therefore be undertaken with this disadvantage, 
that there would nowhere be any certainty as to the rocks 
which would have to be pierced. Of this, however, we may 
be quite sure,—that the water-bearing beds of these rocks 
would be fully charged with water, and that they are of such 
a nature that water would be discharged in large quantities 
into the tunnel. 
A tunnel driven through the Chalk would have this ad- 
vantage,—that it could certainly be taken through the 
Lower Chalk for most, if not all, the way; and though the 
Chalk itself may be fully charged with water, yet it would 
not readily discharge that water into the tunnel, except 
through fissures ; and we have every reason to suppose that 
such fissures would be far less common and of far less 
importance than those met with in Chalk above the sea- 
level. 
Lastly, there is no reason to suppose that any great fault 
will be met with during the progress of the work. 
