Árbók Hins íslenzka fornleifafélags - 01.01.1982, Page 55

BYGGÐALEIFAR Á ÞÓRSMÖRK
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different thicknesses of loess, is present in a rofbarð near the Þuríðarstaðir sites. Both sequences
demonstrate the considerable amount of erosion and deposition that has occured in the recent
past.
A further indication of the intensity of recent processes is provided in a remarkable exposure
near Þuríðarstaðir efri where 2.6 m of deposits exist above the Eyjafjallajökull layer. This ex-
posure is interesting because the deposits are composed of 74 different units; mainly alternations
of grit or sand and loessic material. The sequence continues below the Eyjafjallajökull layer for a
further 2 m but the deposits become very much coarser. The entire sequence appears to represent
a series of fans, perhaps related to different channels. It is even possible that a coarse and a fine
layer represent an annual cycle of different processes. The intriguing aspect is that, apart from
this exposure, the slopes are now grass-covered, indicating that revegetation is possible.
The protected area of Húsadalur, together with the abandoned farm of 1802, present a differ-
ent situation, with its extensive birch cover. In contrast to the 83 cm of loessic soil above the Eyja-
fjallajökull layer in the rofbarð near Steinfinnsstaðir, an exposure near the site indicates only 14
cm of loess above the same layer. There is no indication that substantial amounts of material have
been removed from this site and the facts appear to indicate a much more stable local environ-
ment'. It also suggests that most of the rofbarðs have been built up from material eroded from the
immediately adjacent slopes. Other exposures in Húsadalur indicate rapid revegetation following
soil disturbance and is firm evidence of the recuperative powers of the landscape of sheep are ex-
cluded. A number of processes, such as spring sapping, gullying, slumping, piping and snow
patch erosion, will initiate bare areas, but it is trampling and overgrazing by sheep that prevents
re-vegetation taking place. The bare areas then become enlarged, with wind erosion taking over as
the major process in many localities.
The enclosure of land in Þórsmörk, from the activities of sheep, is an indication that birch for-
est will regenerate. It is also possible that the protected area may provide a base for the re-vegeta-
tion of neighbouring areas. But great care will need to be taken to ensure that recreation does not
achieve what sheep have been prevented from doing..
REFERENCES
Ashwell, I.Y. (1966) Glacial control of wind and soil erosion in Iceland. Annals of the Associ-
ation of American Geographers, 56, 529—540.
Bjarnason, H. (1978) Erosion, tree growth and land regeneration in Iceland. In M.W. Holdgate
and M.J. Woodman (eds.) The breakdown andrestoration of ecosystems, 241—248. New York
and London.
Gilman, K. and Newson, M.D. (1980) Soil pipes and pipeftow: A hydrological study in upland
Wales, Norwich, England.
Haraldsson, H. (1981) The Markarfljót sandur area, southern lceland: sedimentological,
petrographical and stratigraphical studies. Striae, 15, Uppsala.
Þórarinsson, S. (1962) L’erosion éolienne en Islande a la lumiére des etudes tephrochronologi-
ques. Revue de Géomorphologie Dynamique, 13, 107, 124.
APPENDIX II
Ironworking Slags from Steinfinnsstaðir and Þuríðarstaðir efri, Þórsmörk.
by J.G. McDonnell.
The manufacture and working of iron was an industry of major importance in all ”iron age“
communities. The evidence for this industry is provided by the finished products, swords, knives,