142 On the Palwolithie Flint Implements from Knowle. 
the Knowle beds are situated. The rains, too, would have run off 
the clay-with-flints, instead of soaking into the chalk. These 
causes would have been amply sufticient to supply the waters 
needed for the excavation of the now dry vallies. The most im- 
portant of these had its rise a short distance from the eastern 
slope of Martinsell Hill, and after traversing Savernake Forest 
from west to east came out slightly to the north of Knowle. It 
was here joined by other vallies that had also taken their rise in 
the same direction, and the waters from all of them went south- 
eastward into the Valley of Kennett. The period when these vallies 
were formed must be assigned to the Glacial Epoch, which so 
largely affected the surface of the country. England north of the 
Thames is believed to have been covered with an ice-cap; and 
although this did not extend further south the climate must have 
been the same over the whole country. It was one of intense cold, 
varied at intervals by inter-glacial periods accompanied with 
an elevation of temperature. Considerable meltings of the snow 
and ice would take place in these periods, and the water thus ~ 
produced would come down from the high lands in violent floods, 
bringing with it the stones, trees, and other débris that it had 
previously collected, or that obstructed it in its flow. The under- 
lying ground would still be deeply frozen and quite prevent the 
water from soaking away, and the mechanical effect of such a mass 
of water, stone, and other matter would each time tend to deepen 
the vallies. Although many of the implements at Knowle were 
made at the place where they are now found, many others would 
have been brought down from other settlements in this rush of 
water, and Knowle, being a piece of rising ground at the confluence 
of the vallies, would arrest this material, the water receding but 
leaving the heavier matter behind. Many implements are found 
rolled and worn and still retaining.the marks of glacier scratching. 
It is reasonable to suppose that during some one or more of these - 
inter-glacial periods the settlement may have been suddenly 
abandoned by the inhabitants (or overwhelmed by the floods), and 
all their belongings left there. Nothing but the imperishable 
stone implements;have survived and there is no trace of any other 

