MORPHOLOGICAL IMPLICATIONS OF THE 1962-63 WINTER IN NORTH NORTHUMBERLAND

By R. CLARK Portstewart, Northern Ireland

HE continuing interest in snow has been extended recently by further T discussion (Tufnell 1971) of the current morphological consequences of snow persisting in those localities that favour its accumulation and survival. Tufnell found that the sites of major and lingering drifts in the higher parts of the northern Pennines are locations of active erosion, even though the principal development of these sites may have taken place during periods of more severe climate. He commented on the significance of that complex of circumstances and processes generalised under the term ' nivation ', suggesting that it has been rather neglected in morphological studies. This is perhaps more valid with respect to study of current processes in upland Britian than to consideration of landform development during the Pleistocene.

Awareness that nivation continues to play a part, albeit a restricted one, in the shaping of the northern Pennines raises questions of several sorts: of where else in northern England has snow a morphological role, a t least during occasional winters ; of the locational relationship between present snowpatch sites and older ' fossil ' sites of snow and frost action; of when such ' fossil ' sites might have been active; and of whether other manifestations of ice might have morphological effects.

SNOWDRIFT SITES

Tufnell's evidence was drawn from the height range 760-840 m in the Cross Fell - Dun Fell area of the Pennines. Beyond that locality northern England has not a large area of land over 760 m, and much of this is made up of many small areas in the Lake District. The literature and phenomena for that district are considered by Tufnell (1969) but less is known about the rest of the region and about snow action at lower altitudes.

Graham (1969) recorded late-lying snowdrifts in 1969 on west-facing slopes at altitudes down to 440 m in the Cross Fell - Dun Fell area. Thus the question was raised of whether these were associated in location with evidence of nivation having occurred during some earlier cold period, so demonstrating the influence of the helm wind in such a period (Clark 1g7oa). Though Tufnell (1971) noted this question, it remains unresolved.

Consideration of the relationship between present sites of persistent snow- ~

Above right Fig. 2. The Cheviot from the north. The Bizzle, a site of Late Glacial corrie development,

is prominent. The gully entering from the left is where snow lingers longest. Snow drifting from the summit plateau is seen as streaks crossing the lateral hillside drift sites. In shadow is one of the unusually low major drifts of the 1963 winter

Below right Fig. 3. Lingering snow on Thc Chcviot picks out locations of previous nivation processes

associated with lateral drifts

Fig. I . Map showing location of places in north Northumberland mentioned in text. Broken linc indicates snowdrift sites noted in text. The contour height is in feet

drifts and those sites shaped in some earlier period by processes collectively described as nivation and associated with accumulations of deep snow can be developed with the help of evidence from the Cheviot Hills. In the winter of 1962-63, west-facing drifts were formed on the east side of the College Valley at about 330 m, some p m lower than the lowest lateral snow furrows near the top of this hillside. These furrows carry late snow after most sno.wy winters, though not so late as a t higher sites on The Cheviot itself. But in 1963 the high frequency of drifting in strong winds with easterly components meant that much snow was swept from the high plateau east of the College Valley, to build drifts at levels lower than is the case on less severe years.

The lateral furrows below the edge of the plateau indicate that accumulation underthe lee of the plateau at and above 410 m had, in some earlier cold period, produced nivation hollows under the influence of winds with easterly components. This suggests that evidence for earlier nivation could reasonably be looked for a t the sites noted by Graham. Above left Fig. 4.

PhotograQhs by R. Clark Site of flow of saturated soil over still-frozen sole. Homilton Hill. north Northumber-

land. March 1963 Below left Fig. 5: The River Till near Ford, Northumberland. with pancake floes, leads, and pressure

ridges . .

\Vitliin the Cheviots the main locations for deep snow drifts are related to winds with westerly components, and to sites of nivation and other periglacial processes at some earlier time, and they are at a higher altitude than many of the older nivation sites. Sites particularly favourable for present snow accumula- tion and persistence occur, for example, east of Hedgehope (Fig. I) at about 720 m and south-east of The Cheviot at about 815 ni. Both these places appear to have been shaped by earlier nivation processes.

However, it is The Bizzle and the Hen Hole on The Cheviot that have been regarded as the most developed nivation sites -see Fig. 2 (Clark 1970b, Clapperton 1970). An interesting account (Scott 1964) of the survival of snow here in 1963 again shows the importance of drifting in that winter in which snow was present for approximately 260 days on The Cheviot until about 20 July 1963. In Fig. 3 thc lingering snow on The Cheviot picks out locations of previous nivation processes. On tlie low ground flanking the hills the three winter months were 2.2 to 4.5 deg C colder than average and experienced screen frosts on eighty days. These two major sites of snow persistence are at or above about 080 m. This is some 70 m above tlie upper edge of The Bizzle and some 260 m above the lowest clearly-defined nivation hollows that can be ascribed to the Late Glacial cold climates.

The Hen Hole and The Bizzle lie in an area from which many landforms diagnostic of periglacial conditions have been described (Clark 1971)~ but only minor contemporary periglacial phenomena have been recorded. Clapperton (1970) suggested that The Bizzle held morphologically active snow during a Late Glacial cold period, and it is reasonable to suppose that much of the quite abundant evidence for cold-climate processes also was produced during the Late Glacial. It is interesting, therefore, to note a recent report by Goodier and Ball (1969) from North Wales describing the production of stone lobes from a collapsed wall at 600-700 m and the lack of disturbance of early 19th century walls. Their conclusion is that downhill movement of the material near the surface accelerated bv tlie rccurrent formation and melting of internal ice during the Little Ice Age around 1550-1750 A.D. might well have been respons- ible.

I he widespread evidence (Lamb 1963, 1967) for this climatic deterioration and the broadly-dated morpliological evidence from Wales certainly indicate that matching morphological features could be expected in the highest parts of northern England. It would also be interesting to date and validate the stories of midsummer snowball ’ rents for upland farms in the Pennines, for example, in the I-angsett area of the Peak District.

,.

I<AHTH SL1I)ES

The occurrence of winters such as that of 1947 raises the question of whether they had morphological consequences other than those of nivation, frost-heaving and sorting, that is, other consequences of the presence of snow and ice rather than slumping and gullying due to saturation and run-off. In this respect observations made in 1963 at two sites are of relevance. The first site is

the west-facing slope of Honlilton Hill in north Northumberland. A t about 90 m the till-clad slope gives way with sharp inflexion to a valley floor spread of till (boulder clay). This slope had been ploughed in the autumn of 1962 and, like the rest of the area, became deeply frozen. When the thaw had penetrated 250-350 111111, a slice of thawed soil about 40 ni across slid over the lubricated frozen ground and out on to the valley floor, crossing two hedges and a road, and becoming sufficiently fluid to avoid obscuring the inflexion between hillside and valley floor (Fig. 4). In several years of close observation in this neighbour- hood no other case of sliding on such a scale over a frozen sole was observed.

During the same winter the rivers of the area became chokcdwithpancake ice floes (Fig. 5 ) . Snow blowing off riverside fields drifted on to river ice and froze to the banks. Thaw produced two morphological processes. Collapsing blocks of snow camed sheets of alluvium up to 40 mm thick on to the ice and into the river. The break-up of the river ice filled the rivers with grinding floes which abraded the banks, removing more alluvium.

It is not suggested that these occasional processes are important in relation to the more usual course of river action for they were seen in combination only in the winter of 1963, but they do indicate what might be expected in long spells of severe weather.

FROZEN RIVERS

CONCLUSIONS

Thus it is seen that a winter of the 196243 ilk does bring into play processes additional to the usual range, within areas lower than those highest hills of northern England which more often experience very hard winters, and that these processes are associated with the presence of ice. It is also obvious that even such a winter does not in isolation modify a vegetation cover adjusted to more equable conditions, and hence cannot produce the effects that a similar winter would give when part of a sequence of such winters in a periglacial climate.

REFERENCES CLAPPBRTON, C. 111. I 9 7 0

CLARK, R, w o a

GOODIBR. R. and BALL, D. F.

GRAHAM, B. w. LAMB, H. H.

SCOTT, G. TUFNELL. L.

I969

I 963

1967 1964 I969

'97'

The evidence for a Chcviot ice cap. Trans Inst . Brit.

Pcrsistent snowdrift in the northcrn Pennines. Weather,

Aspects of glaciation in Northumberland. Proc. Cumberland Geol. SOC., 2(4), pp. 133-1515

Periglacial landforms and landscapes in Northuinbrr- land. Zbid.. 3(1), pp. 5-20

Recent ground pattern phenomena in the Rhinog mountains, North Wales. Geografiska A nnalev, 51, Ser. A, (3). pp. 121-126

Persistent snowdrift on thc northern Pennines. Weather, 24(10), p. 420

What can we find out about the trciid of our climate? Ibid.. 18(7), pp. 194-216

Britain's changing climate. Geog. ,I.. 133(4) pp. 445-466 Lingering snow on Cheviot. Weather, IS( 7) . pp. 204-205 The range of periglacial phcnomena in northern

England. Biuletyn Pevyglncjalny. 19, pp. L 19-323 Erosion by snow patches in the north Pennines.

Weather, 26(11), pp. 492-498

Geog., 50, pp. 115-127

25(I), P. 4 1

' 95