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.