The Evolution of an English Town | Page 6

of mammoths or straight-tusked elephants
smashed their way through primæval forests and that the hippopotamus
and the woolly or small-nosed rhinoceros frequented the moist country
at the margin of the lake. Packs of wolves howled at night and
terrorised their prey, and in winter other animals from northern parts
would come as far south as Yorkshire. In fact it seems that the northern
and southern groups of animals in Pleistocene times appeared in this
part of England at different seasons of the year and the hyænas of
Kirkdale would, in the opinion of Professor Boyd Dawkins, prey upon
the reindeer at one time of the year and the hippopotamus at another.
Following this period came a time of intense cold, but the conditions
were not so severe as during the Great Glacial times.
[Illustration: Canine tooth or tusk of a Kirkdale bear (Ursus spelacus)]

CHAPTER III
The Vale of Pickering in the Lesser Ice Age
Long before even the earliest players took up their parts in the great
Drama of Human Life which has been progressing for so long in this
portion of England, great changes came about in the aspect of the stage.
These transformations date from the period of Arctic cold, which
caused ice of enormous thickness to form over the whole of
north-western Europe.
Throughout this momentous age in the history of Yorkshire, as far as
we can tell, the flaming sunsets that dyed the ice and snow with
crimson were reflected in no human eyes. In those far-off times, when
the sun was younger and his majesty more imposing than at the present
day, we may imagine a herd of reindeer or a solitary bear standing upon
some ice-covered height and staring wonderingly at the blood-red globe
as it neared the horizon. The tremendous silence that brooded over the
face of the land was seldom broken save by the roar of the torrents, the
reverberating boom of splitting ice, or the whistling and shrieking of

the wind.
The evidences in favour of this glacial period are too apparent to allow
of any contradiction; but although geologists agree as to its existence,
they do not find it easy to absolutely determine its date or its causes.
Croll's theory of the eccentricity of the Earth's orbit[1] as the chief
factor in the great changes of the Earth's climate has now been to a
great extent abandoned, and the approximate date of the Glacial Epoch
of between 240,000 and 80,000 years ago is thus correspondingly
discredited by many geologists. Professor Kendall inclines to the belief
that not more than 25,000 years have elapsed since the departure of the
ice from Yorkshire, the freshness of all the traces of glaciation being
incompatible with a long period of post-glacial time.
[Footnote 1: "Climate and Time." James Croll, 1889.]
The superficial alterations in the appearance of these parts of Yorkshire
were brought about by the huge glaciers which, at that time, choked up
most of the valleys and spread themselves over the watersheds of the
land.
In the warmer seasons of the year, when the Arctic cold relaxed to
some extent, fierce torrents would rush down every available
depression, sweeping along great quantities of detritus and boulders
sawn off and carried sometimes for great distances by the slow-moving
glaciers. The grinding, tearing and cannonading of these streams cut
out courses for themselves wherever they went. In some cases the
stream would occupy an existing hollow or old water-course,
deepening and widening it, but in many instances where the ice blocked
a valley the water would form lakes along the edge of the glacier, and
overflowing across a succession of hill shoulders, would cut deep
notches on the rocky slopes.
Owing to the careful work of Mr C.E. Fox-Strangways and of Professor
Percy F. Kendall, we are able to tell, almost down to details, what took
place in the Vale of Pickering and on the adjacent hills during this
period.

In the map reproduced here we can see the limits of the ice during the
period of its greatest extension. The great ice-sheet of the North Sea
had jammed itself along the Yorkshire coast, covering the lower hills
with glaciers, thus preventing the natural drainage of the ice-free
country inland. The Derwent carrying off the water from some of these
hills found its outlet gradually blocked by the advancing lobe of a
glacier, and the water having accumulated into a lake (named after
Hackness in the map), overflowed along the edge of the ice into the
broad alluvial plain now called the Vale of Pickering. Up to a
considerable height, probably about 200 feet, the drainage of the
Derwent and the other streams flowing into the Vale was imprisoned,
and thus Pickering Lake was formed.
The boulder clay at the seaward end of the