Jökull - 01.12.1986, Blaðsíða 43

Late Holocene Palaeoecology at Ketilsstadir in
Mýrdalur, South Iceland
P.C. BUCKLAND,1 A.J. GERRARD,1 G. LARSEN,2 D.W. PERRY,3 D.R. SAVORY4
& G. SVEINBJARNARDÓTTIR5
abstract
The late arrival of man in the landscape, with the
potential for dating events through tephrochronology,
makes Iceland of considerable interest in the study of
the impact of simple agricultural systems upon a
marginal environment. A multidisciplinary approach
has been adopted for the examination of macrofossils
from a bog at Ketilsstadir in Mýrdalur and these are
discussed in the light of the geomorphological, histori-
cal and tephrochronological record. The natural bog
cnvironment of tussock and pool changes after Land-
nám, with the great influx of inorganic sediment
occasioned by grazing pressure on the surrounding
uplands. The insect fauna becomes more diverse, re-
Jlecting new habitats created by man. The massive
fallout of tephra from the —1357 eruption of Katla had
considerable impact on the bog.although the full pro-
cess of recovery of the biota could not be followed due
to the attendant poor preservation.
INTRODUCTION
For those interested in late Holocene changes in the
environment in Iceland, Mýrdalur in southern Iceland
is a critical region. Lying between Sólheimasandur to
the west and Mýrdalssandur to the east (fig. 1) at the
most southerly point in the country, it is both the
warmest and wettest part óf Iceland with an average
annual temperature of +5.7°C at Vík (1931 — 1960)
and an average yearly rainfall of 2258mm (Eythórsson
& Sigtryggssoni 1971). Any floral or faunal change
resulting from a deteriorating climate should therefore
be registered in Mýrdalur, a last refuge for any
thermophilous elements in the biota. High rainfall
also means that peat bogs are extensive; indeed, the
place-name Mýrdalur may be translated as ‘mire-
dale’. Although most of the bogs have now been
drained to provide better pasturage and increase hay
yields, preservation of organic remains is good and the
many recent ditch sections allow detailed examination
of the stratigraphy, as well as effective sampling. In
any study of environmental change, close dating and
the ability to obtain further samples of the same date
are problems. In Mýrdalur, however, an extensive
study of the tephra layers from Katla and other vol-
canoes (Larsen, 1978; Einarsson et al., 1980) provides
a firm stratigraphic framework for research, which
would be difficult to equal elsewhere. In 1979, there-
fore, a bog (fig. 2) near the modern farm Ketilsstadir
was selected (G.L., P.C.B. & J.R.A. Greig) for an ex-
tensive palaeoecological sampling programme related
to detailed tephrochronological research. Additional
samples were taken in 1980, both to extend the
chronological sequence and to provide further con-
temporaneous samples for comparative study.
LOCATION
Mýrdalur, bounded by sandur to the east and west,
the icecap of Mýrdalsjökull to the north and the
Atlantic Ocean to the south, appears as an oasis of
cultivated land and settlement in a desert of sandur.
1 Department of Geography,
University of Birmingham,
P.O. Box 363,
Birmingham. B15 2TT.
England.
2 Nordic Volcanological Institute,
Geoscience Building,
University oflceland,
Reykjavík 101,
Iceland.
3 Wesley House,
Jesus Lane
Cambridge,
England
4 Faculty of Education,
Memorial Universily of Newfoundland,
St. Johns,
Newfoundland,
Canada.
5 Department of Scandinavian Studies,
University College London,
London, Wl,
England
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