350
THE ESSEX NATURALIST
Bison and Hippopotamus have been frequently found but no
artifacts have been recorded. Both these sites are at, or below,
sea level, but at Walton bones have been recorded from the
gravel above the Red Crag, which also belong to the Great (pen-
ultimate) Interglacial of approximately a quarter of a million
years ago. At Dovercourt, (about 80 ft. O.D.) high level river
gravels have produced numbers of Acheulean flint artifacts, an
industry which succeeded the more primitive Clacton type, but no
fossils appear to have been recorded.
It has therefore been demonstrated that deposits of Great
Interglacial age occur at two levels and the late Samuel
Hazzledine Warren was of the opinion that the high level gravels