Jökull


Jökull - 01.12.1985, Side 26

Jökull - 01.12.1985, Side 26
Little Ice Age glaciation on Hornstrandir quite usable in this context (Thoroddsen 1906, 1911), but according to Eythórsson (1935), Thórarinsson (1943) and John (1977b) the oldest moraines in front of some of the outlet glaciers from the nearby Drangajökull (25 km southeast of Fannarlág) date from the middle of the 18th century, in front of others from 1840—1850. This agrees reasonably well with our tentative dating of the outermost Fannarlág moraines to 1860 or older. The M5 value of about 28 mm at point 0 indicates that some time has passed since the glacier disappeared. If a colonization time of at least 5 years is used and a growth rate of 0.5 mm/yr, a deglaciation date around 1920 is reached. PRESENT GLACIATION Today only four cirques within the studied area of Hornstrandir contain glaciers. Three of these lie inside Hornvík, with their floors around the 500 m level, and one inside Hlöduvík with its floor around the 300 m level (Fig. 13). The Hlöduvík glacier is exceptional, 100- Fig. 15. Lichenometry of the Fannarlág cirque inside Haelavík (Figs. 7 and 14). The measurements were made on moraines and other surfaces uncovered since the Little Ice Age (points 0-8, ending by the arrow), and at two sites outside the area glaciated during the Little Ice Age (points 9 and 10). For each point the mean for the five largest thalli (M5) of Rhizocarpon geographicum agg. and Rh. afpicola, and the size inter- val covered by them, is shown. The sloping dashed line illustrates what kind of pattern would be expected if the glacier retreat had been constant. 15. mynd. Fléttumœl- ing fyrir Fannarlág. Fléttur voru mældar á jökulgörðum og öðrum flötum sem voru undir ís á Litlu Isöld. Til viðmiðunar var einnig mœlt á tveim stöðum sem voru íslausir þá (punktar 9 og 10). Skyggða beltið sýnir niður- stöður mælinganna, en hallandi brotalína sýnir hvaða mynstur jafnhröð hopun jökulsins hefði orsakað. Fig. 14. Little Ice Age moraines in the Fannarlág cirque inside Haelavík. Photo 18/7 1983. 14. mynd. Jökulgarð- ar frá Litlu Isöld í Fannarlág í Hœlavík. since several higher situated cirques.in its neighbour- hood are unglaciated. In all, the total area of the four cirque glaciers on northern Hornstrandir today is only 1.0—1.5 km2. To this come an undefined number of small ice-cored perennial snowdrifts and firns at various, mostly high, altitudes. The cirques containing ice today contained much larger (Hlöduvík) or sorne- what larger (Hornvík) glaciers during the Little Ice Age (Fig. 13). The present ELA for cirques on northernmost Horn- strandir lies around or slightly above 500 m. The general glaciation limit lies above 600 m. This should be com- pared with an ELA, in an open position, at 700—800 m on Drangajökull (Th. Einarsson 1968). LATE FLANDRIAN TRANSGRESSION Today’s sea level on Hornstrandir has risen in com- parison with earlier parts of the Flandrian. This is indicated by the coastal erosion of the low level fluvial/ lacustrine sediments in Haelavík — with simultaneous deposition of very coarse beach material onto parts of the cliff face. Distinct erosional cuts in the fronts of talus cones, especially below Kögur north of Fljótavík (Fig. 16) probably also indicate a presently rising sea level. SUMMARY AND DISCUSSION (1) During the last (Weichselian) glaciation the Vest- firdir peninsula was probably covered by an indepen- dent ice cap (Thoroddsen 1906, Thórarinsson 1937, Th. Einarsson 1968, John 1977a, Sigurvinsson 1983). The 24 JÖKULL 35. ÁR
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