24 THE ESSEX NATURALIST
be wrong, and the unmistakable track which we followed from
Semer to Woolpit and Stowlangtoft turned out to be the southern
extension of Peddar Way, previously discovered and reported by
Copinger Hill [7]. It is significant that no boulders of conglomerate
were found upon this track, and reference to the maps of the
Geological Survey showed that we had reached the northern
limit of the Reading Beds, of which puddingstone is a constituent
rock. Unless therefore our track-builder had laboriously trans-
ported his stones over ever-increasing distances—and we had
found no evidence of this anywhere else upon the track—we were
prepared to accept other forms of conglomerate, from the local
glacial gravels.
The last specimens of true puddingstone were found at the
village of Kersey, one marking the ford at the bottom of the
village street, the other at the northern end of the village (Plate 4).
These pointed towards the great block of ferruginous conglom-
erate in the orchard at Drakestone Green, previously known to
us; and in the same line two others were found at Chelsworth.
These five boulders, distributed over a distance of two miles,
showed a slight change of direction to the north-north-west, and
showed that the ford in the village of Kersey was the most easterly
point reached by the track.
From Chelsworth to Thetford is a distance of about thirty
miles, and up to the present this section has not been given a detailed
examination, yet we have found two boulders upon it. Both
are "pagan" stones associated with churches—the first being in
the churchyard at Thurston, and the second just outside the
churchyard at Little Livermere. We are confident that many
others lie along this section awaiting discovery. The old ford over
the Little Ouse at Thetford may still be seen beside the modern
road-bridge, and here are two conglomerate blocks lying one on
either bank. This ford ranks in antiquity with that over the River
Ver at St. Albans, and carried the track to the final few miles of
its way to Grimes Graves, through what is today Thetford town,
and over Gallows Hill.
Although we had for a long time suspected that the ancient
flint-mines at Grimes Graves were the ultimate objective of the
track, it was not until the summer of 1951 that we made the im-
portant discovery of a conglomerate block upon this site, a cir-
cumstance which we regard as the final proof of our deductions.
It was found in a singularly remarkable manner. We had con-
sulted the Proceedings of the Prehistoric Society of East Anglia
for accounts of the excavations at Grimes Graves, and had noticed
in a sketch plan published in 1915 [8] a feature described as an
"Erratic Boulder", resting on the edge of a "clay-pit", south-west
of the mining area. It was sufficiently remarkable as the only