Page 292 - Fundamentals of Geomorphology

GLACIAL AND GLACIOFLUVIAL LANDSCAPES 275

addressed by relying on the low permeability of till would prevent leachates from leaking. It also iden-
the till and reworking the till around the edges tified other sites in south Norfolk that would be
of the site to remove potentially leaky sand-lenses suitable landfill sites, including the extensive sand
in its upper layers. In August 1993, after a public and gravel deposits along the margins of the River
inquiry into the Hardwick site, planning permis- Yare and its tributaries. Landraising in a till plain
sion was refused, partly because knowledge of the is also unwelcome on geomorphological grounds,
site’s geology and land drainage was inadequate and unless perhaps the resulting hill should be screened
alternative sites were available. Research into the site by woodland. A lesson from this case study is that
prompted by the proposal suggested that leachate knowledge of Quaternary geology is central to the
containment was a real problem and that Norfolk planning and design of landfill in areas of glacial
County Council was mistaken in believing that the sediments.

SUMMARY shrinkthecryosphereanddestroyQuaternarylandforms.
Conversely, knowledge of Quaternary sediments is indis-
Ice covers about 10 per cent of the land surface, although pensable in the judicious use of glacially derived resources
18,000 years ago it covered 32 per cent. Most of (such as sands and gravels) and in the siting of such
the ice is in polar regions. Glaciers come in a variety features as landfill sites.
of forms and sizes: inlandsis, ice sheets, ice caps, ice
shelves, ice shields, cirque glaciers, valley glaciers, and ESSAY QUESTIONS
other small glaciers. Glaciers have an accumulation zone,
where ice is produced, and an ablation zone, where ice 1 How does ice flow?
is destroyed. Erosion by ice creates a wealth of land-
forms by abrasion, by fracture, by crushing, and by 2 How does ice fashion landforms?
eroding a mountain mass. Examples include glacially 3 Appraise the evidence for
scoured regions, glacial troughs, striated bedrock, trough catastrophic glaciofluvial events.
heads, cirques, flyggbergs, crescentic gouges, horns, and
nunataks. Debris laid down by ice produces an equal
variety of landforms. Supraglacial deposits form lat-
eral moraines, medial moraines, dirt cones, erratics, and FURTHER READING
many more features. Subglacial forms include drumlins
and crags-and-tails. Terminal moraines, push moraines, Ballantyne, C. K. (2002) Paraglacial geomorphology.
hummocky moraines, and other forms occur at ice mar- Quaternary Science Reviews 21, 1935–2017.
gins. Meltwater, which issues from glaciers in copious A superb and well-illustrated review of paraglacial geo-
amounts during the spring, cuts valleys and deposits morphology.
eskers beneath the ice, produces meltwater channels and Benn, D. I. and Evans, D. J. A. (1998) Glaciers and
kames at the edge of the ice, and fashions a variety Glaciation. London: Arnold.
of landforms ahead of the ice, including spectacular An excellent text.
scablands and spillways, outwash plains, and, on a
much smaller scale, kettle holes. A variety of paraglacial Bennett, M. R. and Glasser, N. F. (1996) Glacial
landforms develop immediately glaciers melt. Humans Geology: Ice Sheets and Landforms. Chichester: John
interact with glacial landscapes. Their current industrial Wiley & Sons.
and domestic activities may, through global warming, Another very useful text.