Geoscience Reference
In-Depth Information
common with those above 2700 metres in the Alps. Locally in this 'arctic-alpine' soil
zone in Britain, one finds 'patterned ground' terrain (
Fig. 10
) and soils characteristic
of high alpine and sub-arctic locations. North of the transect position in
Figure 9
, such
features are found on hills as low as 275 metres altitude on suitable rocks in Orkney
and Shetland. Well to the south, in the Lake District and North Wales, these active
arctic-alpine features occur only in limited areas above about 900 metres, although
relic frost-action landforms, from earlier climatic conditions, are still recognizable at
lower altitudes.
F
IG. 10
'Patterned ground', produced by frost and wind action in the 'arctic' soil zone, can occur at low altitudes
in northern Britain, as here on Hoy, Orkney (Photograph D.F.B.)
The lower, 'climatic peat', zone of
Figure 9
is at about 100 metres altitude at the
western end of the transect, and rises to about 400 metres on the eastern hill areas.
To the north, in the Western Isles and on the north-western Scottish coasts, it comes
down to sea level. It is characterized by moorland vegetation on moderately drained
and poorly drained soils with peaty surface horizons, and on associated deep peats,
the latter being dominant in many Scottish and Pennine areas. In North Wales, a sim-
ilar transect from west to east shows that such moorland soils occur above an average
of 350 metres in the wetter west, and above 550 metres in the highest hills of the drier
east.
Within these vertical zones, there are of course major soil contrasts brought
about locally by different parent materials, and by different landform features such as
locations on hill crests, upper and lower slopes, or in basin sites. Some such soil con-
