Jökull - 01.12.1967, Blaðsíða 38

TABLE I
The retreat of Hagafellsjökull according to Eythorsson 1962, 1963, 1964 and 1966, Wright 1933,
Green 1932 and the present author
Hagafellsjökull Eystri Hagafellsjökull Ytri
Time intervals m m/year m m/year
ca. 1890-1902 f- 115 - 10 v
1902-1929 -f- 635 -f- 20 V -f- 792 f- 18
1929-1934 -f- 600 -f- 120 J
1934-1938 -f- 400 -f- 100 ] -f- 160 f- 32
1938-1939 4- 100 -f- 100 i
1939-1942 -r- 250 -f- 83 -f- 170 f- 57
1942-1945 -f- 225 - 75 5
1945-1948 1 -f-290 f- 48
1948-1950 1 H- 300 H- 60 J H- 168 f- 84
1950-1956 H-500 -f- 83 -f- 168 f- 28
1956-1957 i -f- 50 f- 50
1957-1960 -f- 375 -f- 94 -i
-f- 250 -f- 63
1960-1961 -f- 50 -f- 50 J
1961-1962 -| -f- 90 f- 90
1962-1963 H- 155 -f- 78 J f- 320 f- 160
1963-1964 ~ 100 -f- 100 J
1964-1965 H- 128 f- 128 1
1965-1966 -f- 50 -f- 50 J -f- 175 f- 88
Total 1890-1966 -f- 3783 1 50 f- 2633 f- 35
Eystri (Fig. 7) were carefully carriecl out on the
maps from 1938 and 1945 and the result is
drawn in liypsographic curves on Fig. 8, which
then were used in computing the decrease in
volume of the glacier. The true volume of the
glacier cannot be computed as its sub-surface
is unknown. The computed volume is there-
fore as well the volume of the land on which
the glacier was resting in the year 1938 as of
the glacier itself.
The area, which became deglaciated during
the years 1938 to 1945, was measured separately
(Fig. 8) ancl subtracted in volume calculations.
The difference in volume between these years
is due to the glacial recession. The net ablation
in each contour interval is found as a differ-
ence between the two hypsographic curves,
when the appropriate deglaciated area has been
subtracted. Table V shows how the ablation was
computed.
The measured area between the 880 m and
900 m contour lines was 2.2 km2. Thus the
ablation per km2 has been 15.9 x 10° m3. In
TABLE II
The average retreat of Hagafellsjökull
Hagafells- Hagafells-
Number jökull jökull
of Eystri Ytri
Periods years m/year m/year
1922-1934 ... 12 85-100 45-60
1934-1945 ... 11 87 43
1945-1956 ... 11 73 44
1956-1966 ... 10 86 89
TABLE III The area of Hagafellsjöliull Eystri (Fig. 1)
ca. 1890 at different times 54.3 km2
1938 41.9 -
1945 36.2 -
1960 29.7 -
1966 26.1 - *
* Calculated value.
272 JÖKULL 17. ÁR