Great difficulties have often been encountered by engineers in carrying
earth embankments across low grounds, which, under a fair, green surface,
concealed the remains of ancient bogs, sometimes of great depth. Thus,
on the Leeds and Bradford Extension, about 600 tons of stone and earth
were daily cast into an embankment near Bingley, and each morning the
stuff thrown in on the preceding day was found to have disappeared. This
went on for many weeks, the bank, however, gradually advancing, and
forcing up on either side a spongy black ridge of moss. On the
South-Western Railway a heavy embankment, about fifty feet high, crossed
a piece of ground near Newham, the surface of which seemed to be
perfectly sound and firm. Twenty feet, however, beneath the surface an
old bog lay concealed; and the ground giving way, the fluid, pressed from
beneath the embankment, raised the adjacent meadows in all directions
like waves of the sea. A culvert, which permitted the flow of a brook
under the bank, was forced down, the passage of the water entirely
stopped, and several thousand acres of the finest land in Hampshire would
have been flooded but for the exertions of the engineer, who completed a
new culvert just as the other had become completely closed. The
Newton-green embankment, on the Sheffield and Manchester line, gave way
in like manner, and to such an extent as to spread out two or three times
its original width. In this case it was found necessary to carry the
line across the parts which yielded, under strong timber shores. On the
Dundalk and Enniskillen line a heavy embankment twenty feet high suddenly
disappeared one night in the bog of Meghernakill, nearly adjoining the
river Fane. The bed of the river was forced up, and the flow of the
water for the time was stopped, and the surrounding country heavily
flooded. A concealed bog of even greater extent, on the Durham and
Sunderland Railway, near Aycliff, was crossed by means of a
double-planked road, about two miles in length. A few weeks after the
line had been opened, part of the road sank one night entirely out of
sight. The defect was made good merely by extending the floating surface
of the road at this portion of the bog.
—_Quarterly Review_.