Hull Geological Society
The Yorkshire Chalk
A geomorphological walk from Thixendale
Start from the Cross Keys pub in Thixendale and take the field path NE along Water Dale, crossing the entrance to Court Dale and climb up to a small coppice.
From here the view shows some typical features of dry valleys. The slopes of Water Dale are markedly asymmetric, the NW-facing slope being much the steeper. There is no simple explanation for this. It is not due to differences in rock type as everything is chalk and it does not appear to be related to aspect since other dry valleys parallel to Water Dale have symmetrical sides. There is an abrupt change in slope onto the flat floor of the valley which here lies at about 120m OD and close to the base of the Chalk. The underlying Kimmeridge Clay would explain the presence of standing water on the valley floor after wet weather, and, of course the name of the valley.
Across Water Dale to the SE an old pit is visible on the hillside. Note that this exposes no chalk in situ but only chalk rubble. This rubbly layer covers much of the
The melting snows of early summer would have produced a lot of surface water which was unable to drain through the frozen subsoil. The flat floor of the valley would have been occupied by a stream of braided channels flowing through drifts of chalk rubble.
Honey Dale divides and the larger fork, Back Dale, narrows and appears partly blocked by rounded protuberances of its southern slope. The reason for this will become more apparent later in the walk.
Something of the
patch of wet ground is known as “Vessey ponds”. Large quantities of flint
artefacts have been found around the ponds and it is thought that in
pre-historic times they provided a water supply on the otherwise dry
there is a prominent chalk scree, to what extent man-made is uncertain. It gives
a good illustration of the nature of the
This small isolated hill is a good example of a deep rotational land slip. The steep slope to the S has failed and a slice has slipped down onto the valley floor partly blocking it. Looking to the E along Back Dale similar slips can be seen. The eastern end of these were viewed from Stop 2 earlier in the walk. Such landslips would have been very active under permafrost conditions during the last glaciation.
From Vessey Hill a steep
climb S brings you back onto the
Notice the contrast in the form
of the two dry valleys to the W.
Water Dale has a sinuous course with
interlocking spurs but Thixendale is quite straight. I offer no explanation but
these differences certainly add to the beauty and diversity of
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