Jökull


Jökull - 01.12.1956, Síða 16

Jökull - 01.12.1956, Síða 16
Fig. 13. The moraine hillocks Kvíárhólar. To their left the slope of Kviármýrarkambur. Photo S. Thorarinsson 16 Sept. 1955. (Ives ancl King 1955, p. 478). My impression from a short visit in 1945 was that these “moraines” might be early postglacial dead ice moraines. There is no doubt that they are prehistoric, but nothing more can as yet be said with certainty about their age. Also here a tephrochronological study woulcl probably prove useful for dating the moraines. Finally it should be mentioned tliat shortly W of the road between Svínafell ancl Sandfell, ab. 2 km in front of the present snout of Fall- jökull, there are prehistoric terminal moraines called Rasshólar. They could be of the same age as the moraines in Morsárdalur and Staclar- dalur. The conclusions cjuoted at the beginning of this paper, viz. that the moraines which were formed during the advance of the glaciers around the northernmost Atlantic in the 18th and 19th centuries mark their maximum extent in historical and probably even in postglacial time, are in my opinion still valid for the bia; outlets of Vatnajökull, but the tephrochrono- logical studies in Oræfi related in this paper support the view that some of the outlets of Oræfajökull advanced in early Subatlantic. Time as far ancl even a little further than in the 18th and 19th centuries. The reason why the outlets of Vatnajökull proper did not in early Subatlantic Time advance as far as the outlets of Öræfajökull, compared with their re- cent advances, might then simply be that at the end of the Postglacial Warm Period Vatna- jökull proper was proportionally more reduced in area than the higher and more alpine Öræfa- jökull (cf. Eythórsson 1951 a). The rising of the firn line during the Warm Period liad a greater reducing effect on the big Vatnajökull outlets with their relatively flat spoonshaped intake areas than it hacl on the steep alpine Öræfa- jökull outlets. But we must also take into con- sideration that Öræfajökull is an active volcano, as that may have affected its outlet glaciers. REFERENCES: Ahlmann, H. W:son: 1933. Scientific Results of the Swedish-Norwegian Arctic Expedition. Part VIII. Glaciology. Geogr. Ann. Stockh., 15: 161-216, 312-348. Stockholm. — Glaciological Research on the North At- lantic Coasts. R. G. S. Research Series No 1. London. Bárdarson, G. G.: Islands Gletscher, Vísindafál. Isl. 1. Reykjavík. Eythórsson, }.: 1935. On the Variations of Glaciers in Iceland. I. Drangajökull. Geogr. Ann. Stockh. — 1949. Variations of Glaciers in Iceland 1930 -1947. Journ. Glaciol., 1: 250-252. Cambr. — 1951 a. Þykkt Vatnjökuls. Jökull, 1: 1—6. Reykjavík. 14

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Jökull

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