_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 Vale seems to have been capped
by ice of a thickness of nearly 100 feet which efficiently contained the
waters of the lake until they overflowed through a depression among the
hills to the south of Malton. If the waters escaped by any other outlet to
the west near Gilling and Coxwold, it can scarcely have been more than a
temporary affair compared to the overflow that produced the gorge at
Kirkham Abbey, as the Gilling Gap was itself closed by the great glacier
descending the Vale of York. The overflow of the lake by this route, south
of Malton, must have worn a channel down to a lower level than 130 feet
O.D. before the ice retreated from the seaward end of the Vale, otherwise
the escape would have taken place over the low hills blocking the valley
in that direction and the normal course of the drainage of the country
would have been resumed. The southern overflow evidently dug its way
through the hills fast enough to maintain that outlet, and at the present
time the narrow gorge at Kirkham Abbey is only 50 feet above sea level,
and the hills through which the Derwent passes at this point are from 200
to 225 feet high.
[Illustration: A Map of North-Eastern Yorkshire showing Lake Pickering
during the maximum extension of the ice. The area covered by ice is left
unshaded. The arrows show the direction of the glacier movements.
(Reproduced from the _Quarterly Journal of the Geological Society_, by
permission of Professor Percy F. Kendall.)]
As the waters of the lake gradually drained away, the Vale was left in a
marshy state until the rivers gradually formed channels for themselves. In
recent times drainage canals have been cut and the streams embanked, so
that there is little to remind one of the existence of the lake save for
the hamlet still known as The Marishes. The name is quite obviously a
corruption of marshes, for this form is still in use in these parts, but
it is interesting to know that Milton spelt the word in the same way as
the name of this village, and in Ezekiel xlvii. II we find: "But the miry
places thereof, and the marishes thereof, shall not be healed." The ease
with which a lake could again be formed in the Vale was demonstrated in
October 1903 after the phenomenally wet summer and autumn of that year, by
a flood that covered the fields for miles and in several places half
submerged the hedges and washed away the corn stooks.
The evidence in favour of the existence of Lake Pickering is so ample
that, according to Professor Kendall, it may be placed "among the
well-established facts of glacial geology."[1]
[Footnote 1: _Quarterly Journal of the Geological Society_, vol. lviii.
part 3, No. 231, p. 501.]
We have thus an accredited explanation for the extraordinary behaviour of
the river Derwent and its tributaries, including practically the whole of
the drainage south of the Esk, which instead of taking the obviously
simple and direct course to the sea, flow in the opposite direction to the
slope of the rocks and the grain of the country. After passing through the
ravine at Kirkham Abbey the stream eventually mingles with the Ouse, and
thus finds its way to the Humber.
The splendid cañon to the north of Pickering, known as Newton Dale, with
its precipitous sides rising to a height of 300 or even 400 feet, must
have assumed its present proportions principally during the glacial period
when it formed an overflow valley from a lake held up by ice in the
neighbourhood of Fen Bogs and Eller Beck. This great gorge is tenanted at
the present time by Pickering Beck, an exceedingly small stream, which now
carries off all the surface drainage and must therefore be only remotely
related to its great precursor that carved this enormous trench out of the
limestone tableland. Compared to the torrential rushes of water carrying
along huge quantities of gravel and boulders that must have flowed from
the lake at the upper end, Newton Dale can almost be considered a dry and
abandoned valley.
[Illustration: A Diagrammatic View of Newton Dale during the Lesser Ice
Age. The overflow of the glacier dammed lakes at the head of the dale came
down Newton Dale and poured into Lake Pickering.]
At Fen Bogs, where there is a great depth of peat, Professor Kendall has
discovered that if it were cleared out, "the channel through the watershed
would appear as a clean cut, 75 feet deep." The results of the gouging
operations of this glacier stream are further in evidence where the valley
enters the Vale of Pickering, for at that point a great delta was formed.
This fan-shaped accumulation of bouldery gravel is marked in the
geological survey maps as covering a space of about two square miles south
of Pickering, but the deposit is probably much larger, for Dr. Thornton
Comber states that the gravel extends all the way to Riseborough and is
found about 6 feet below the surface, everywhere digging has taken place
in that direction. The delta is partly composed of rounded stones about 2
feet in diameter. These generally belong to the hard gritstone of the
moors through which Newton Dale has been carved. Dr. Comber also mentioned
the discovery of a whinstone from the great Cleveland Dyke, composed of
basaltic rock, that traverses the hills near Egton and Sleights Moor, two
miles above the intake of Newton Dale at Fen Bogs.
The existence of this gravel as far towards the west as Riseborough,
suggests that the delta is really of much greater magnitude than that
indicated in the survey map. It has also been proved that Newton Dale
ceased its functions as a lake overflow, through the retreat of the
ice-sheet above Eskdale long before the Glacial Period terminated, and
this would suggest an explanation for the layer of Warp (an alluvial
deposit of turbid lake waters) which partially covers the delta. The
fierce torrents that poured into Lake Pickering down the steep gradient of
this canon would require an exit of equal proportions, and it seems
reasonable to suppose that the gorge at Kirkham Abbey was chiefly worn at
the same time as Newton Dale.
[Illustration: Diagrammatic view showing the presumed position of the ice
at the eastern end of the Vale of Pickering during the Lesser Glacial
epoch. The river Derwent is shown overflowing along the edge of the
glacier.]
Another delta was formed by the upper course of the Derwent to which I
have already alluded. In this instance, the water flowed along the edge of
the ice and cut out a shelf on the hill slopes near Hutton Buscel, and the
detritus was carried to the front of the glacier. This deposit terminates
in a crescent-shape and now forms the slightly elevated ground upon which
Wykeham Abbey stands. The Norse word Wyke or Vik means a creek or bay, and
the fact that such a name was given to this spot would suggest that the
Vale was more than marshy in Danish times, and perhaps it even contained
enough water to float shallow draught boats. Flotmanby is another
suggestive name occurring at the eastern corner of the lake about four
miles from Filey. In modern Danish _flotman_ means a waterman or ferryman,
and as there is, and was then, no river near Flotmanby, there is ground
for believing that the Danes who settled at this spot found it necessary
to ferry across the corner of the lake. Before the Glacial Period, the
Vale of Pickering was beyond doubt from 100-150 feet deeper at the seaward
end than at the present time, and even as far up the Valley as Malton the
rock floor beneath the deposit of Kimeridge clay is below the level of the
sea.