Jökull - 01.12.1966, Blaðsíða 8

so-
100
method o£ constructing the curves is the fol-
lowing. For the decrease o£ glacier load we use
tlie curve Gv o£ Fig. 2. The ordinate of the
curve for absolute rise o£ the locality be v (posi-
tive downward), its maximum value ym at 18.000
B.P. is taken to correspond to equilibrium
under full load, ordinate o£ Gv = 1. The
rapidity o£ rise of the locality is then dy/dt =
— k (y — ym • Gv), where k is a constant for the
country, depending on viscosity and the dia-
Absolute rise of the Reykjavík area. Si
: rise of absolute sea-level (cf. Fig. 2). 1, 2, 3
are theoretical curves £or the rise of the
Reykjavík area. Time scale at top.
6. mynd. Ris Reykjavíkursvœcíisins, línur 1, 2, 3
og 4, borið saman við ris sjávar, Si og So.
meter of the whole depression. Two values for
ym have been selected (125 m and 135 m) and
three values for k (i/í>, 1, The correspond-
ing four curves are shown in Fig. 6.
By comparison of these curves with Si of
Fairbridge the relative height of sea-level at
various epochs can be found as shown in
Table II.
As criteria for the selection of the fitting
curve we have the demands that the highest
sea-level must come near 43 m, the maximum
height of the raised beach at the locality, and
that the curve must intersect Si near the time
9000 B.P. The intersection for curve 3 is 8500
B.P. ancl for curve 4 it is 8300 B.P.
It is clear that ym must be considerably larger
than 100 m, otherwise the curve would have
to be flat in the beginning and later rise rather
suddenly. But this is not possible if the early
and late parts shall be consistent, i.e. if k is
TABLE II.
Relative heights of sea-level at Reykjavík at various time.
y.n k T = 17.3 15.8 13.3 12.0 11.0 10.0 9.0 8.0 7.5 7.0 6.5 6.0 x 103 B.P
125 1 Curve i 25 m 42 41 37 39 24 19 - -11 - - 13 -7 - - 10 0
125 V% — 2 25 43 48 46 52 38 35 8 4 7 2 10
135 3/2 — 3 35 51 46 39 40 23 15 - - 19 - - 18 -9 - - 11 0
135 1 — 4 35 52 49 44 45 29 22 - - 10 - - 13 -7 - - 10 0
162 JÖKULL