NOTICES OF OTHER SIMILAR REMAINS IN THE NEIGHBOURHOOD. 37
More satisfactory evidence is found by returning to the outside
of the dam and taking its southern end. When the overflow was
transferred to this end, a broad and deep channel seems to have
been excavated for it. This channel can still be traced. Taking a
circuitous course, it enters the original bed of the stream about 70
yards below the dam. This channel was an effectual conductor of
the overflow for a very long time, and probably represents the period
of active occupation or use of the lake. The work of keeping this
channel clear and repairing the dam must have involved a continual
shifting of material and addition of new gravel to replace the waste.
There are various hollows in the vicinity which were perhaps made
for this purpose.
A time, however, came when these labours ceased, and this
period of decadence has also left its mark. The channel was first
choked at about 30 yards from the dam, and the water then took
a new course across the enclosure made by the artificial channel
and the brook's original course. This new channel also succumbed
in course of time, and various other minor ones were made from time
to time, which have left faint traces. During this time, or in the
later years of the lake's existence, the dam was also neglected. The
process seems to have been that the overflow channel became
stopped at the dam, and lateral erosion commenced which gradually
extended along the dam for about 20 yards, and has reduced it 4
feet in height. The waste now lies behind the dam and forms an
inclined plane at that place to its summit.
Finally there came a time when a breach was made in the dam
at its deepest part and the brook resumed something like its original
course. There are some considerations which lead us to believe
that this final drainage of the lake was effected a very long time ago,
and is, perhaps, only measurable by centuries. One consideration is
the road skirting the northern end of the dam. This has been worn
down about 4 feet since the breach was made—were the lake now