Jökull


Jökull - 01.12.1986, Side 46

Jökull - 01.12.1986, Side 46
Fig. 4. Ketilsstadir: section at KE/ SUPPL. showing the tephra of the — 1357 eruption filling a peat cutting. - Mynd 4. Snið. KE/SUPPL. í mýri við Ketilsstaði. Það sýnir forna mó- gröf sem fylltist af gjósku í Kötlugosi um 1357. Fig. 5. The stratigraphy of section BRl at Ketilsstad- ir (1979). — Mynd 5. Snið BR I í mýri við Ketilsstaði (1979). Jarðvegur og gjóskulög. (Katla —1357) also sealed a midden at Fell containing an abundance of fish bones (Thórarinsson, 1972; Einarsson, 1975,21; Einarsson etal., 1980,4). TEPHROCHRONOLOGICAL RECORD The Mýrdalur district lies at the margin of the Eastern Volcanic Zone in southern Iceland. It has repeatedly been affected by tephra fall from the sub- glacial volcano Katla, below the icecap óf Mýrdals- jökull some 20km to the north, and less frequently by tephra from more distant sources. The tephra forms distinct layers within the soil, which are well exposed in drainage ditches such as those found at the Ketils- stadir bog (fig. 4). The more or less continuous layers can be easily followed within the bog and conveni- ently used as stratigraphic markers; the age of several tephra layers is known, providing dated isochrones. Such dated horizons are, however, restricted to the last 1100 years, although earlier layers occur at the base of the exposed succession. The tephra layers in the Ketilsstadir bog were identified by comparison with other recently studied soil sections in this area (Larsen, 1978; Einarsson et al., 1980). The stratigraphy is shown in figure 5. Black U* vi m ATT TEPHRA 5 mm TEPHRA 5 mm SAMPLED IHEKLA 1597] KATLA 15BCj TEPHRA 4 mm TEPHRA 3 mm TEPHRA 10mm CÖÁRSÉ ( PUMÍCES TÖ 5mm). BLACK (N1) TEPHRA [KATLA -1357] 140 mm .....KE 1/1 ..KE 1/2; 2/1; 3/1; 4/1 Kfj •OLIVE GREY (5yr 3/2).......... TEPHRA 10mm [HEKLA 1341] TEPHRA 3mm MODERATE ÐROWN (5yr 3-4/4) FIBROUS PEAT WITH SOME TRACE OF LENTICULAR BEDDING 260mm GREYISH BLACK (N2) TEPHRA 42.5 mm GRÉYISH BLACK (N2) TEPHRÁ ÍÖmm.... ÖLÍVÉ BRÖWN (5y 4|2) TEPHRÁ...... [LANDAM ASHl 25mm BLÁCK TÉPHRÁ 15mm BLACK TEPHRA 20-30rr S i' d± V) (’n ^ ■ 53 ¥7 i n lilu MODERATE BROWN (5yr 3|4) FIBROUS PEAT* 300 mm GREYISH BLACK (N 2) TEPHRA 40 rt GREYISH BROWN (5yr 3|2) FIBROUS PEAT 180 mm DARK OLIVE GREY (5yr2/2) TEPHRA 70-80 mm BLACK TEPHRA 60mm TEPHRA 10mm ( Basa of ditch)..........._.KE 1115 .ke/suppl. ...KE/1 3; Br 1113; Br 1 /12 Br 1/13; KE1/6; 2/3; 3/3; 4|3 Br 1/14 .Br 1/15; KE 1/4 . KE 1/7 44

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