The physical environment - Fundamentals of the Physical Environment - page 5

Plate 1.1 The head of Upper Wharfedale is centre left, with the steeper left-bank tributary of Gill Beck coming from centre right .
The village of Kettlewell lies at the confluence.
Photo: Ken Atkinson

meeting Buckden Pike, the ice split into a stream flowing
north-eastwards along Bishopdale and into Wensleydale
and a stream flowing south-eastwards down Wharfedale.
The Wharfedale ice was joined by Littondale ice, and the
combined ice stream eroded the truncated spur of Kilnsey
Crag in Great Scar Limestone ( Plate 1.2 ). The power of
glacial erosion is evidenced by the classic U-shaped valleys
of Upper Wharfedale, Littondale and Bishopdale.
During periods of glacial retreat, moraines were
deposited in valley bottoms and on lower valley side
slopes. These are thought by some geographers to have
initially dammed the river flow but to have been breached
since. According to this hypothesis, the present flat alluvial
floor of Upper Wharfedale held lakes in late glacial and
early postglacial times. During deglaciation, when sub-
surface drainage was prevented by permafrost , meltwaters
eroded marginal channels along valley sides. At Conistone
village the impressive ravine of Conistone Dib narrows to
1 m width in places, with fluvial potholes evident on the
side walls. This dramatic gorge was sculptured by a
glaciofluvial stream issuing from the front of or from
beneath a retreating glacier ( Plate 1.3 ).
Since the Pleistocene epoch, geomorphic activity in
Upper Wharfedale has been of two main types. First,
weathering and erosion of hill slopes have produced
valley-side scars and small screes. Second, the channels

GEOLOGY

Upper Wharfedale
Environmental
System

CLIMATE
AND
HYDROLOGY

PHYSIOGRAPHIC
EVOLUTION

Vegetation Soils Land Use

ECOLOGICAL
AND
ANTHROPOGENIC
HISTORY

Figure 1.2 Environmental and human controls on the Upper
Wharfedale environmental system.

In terms of physiographic evolution, the most influ-
ential events were the many glacial episodes during the
Pleistocene epoch of the Quaternary period (Atkinson, in
Butlin 2003). During the most recent glaciation, namely
the Devensian , glaciers entered Upper Wharfedale from
local ice accumulation centres on plateau summits in
the Pennine uplands such as Langstrothdale Chase,
and flowed south-eastwards down Langstrothdale. On