Rit (Vísindafélag Íslendinga) - 01.06.1923, Síða 108

104
(raised terraces) and round the outermost part of the mount-
ains between them (rock-terraces). In the entrances to some
valleys these marine terraces form barriers that are some-
what higher than further up the valleys. It appears that the
glaciers extended, for a considerable period, as far as the
entrances to the valleys, and piled up terminal moraines,
which the sea at a later period levelled somewhat and
formed into terraces. By this time the glaciers must have
left the entrances to the valleys.
4. Marine ierraces of more recent íitnes and the dis-
tinction behveen them and older terraces, (pp. 60—65).
Observations are here recorded, which show that old
marine formations are general and continuous in all the ex-
plored tract up to a height of 40—50 m. above sea-level.
Terraces are most common 20 — 30 m. above sea-level ad-
vancing evenly up to 40 — 50 m. above sea-level. Above
that height marine formations are indistinct and not con-
tinuous. At the height of 40 — 50 m. there is in many places
a clear line of demarcation between marine formations that
lie above and below this height:
a) Rock terraces, sea-cliffs and gravel terraces are gener-
ally especially distinct at this elevation, and steep ascents
or gravel slopes run from the terraces found at this height
up to the higher terraces.
b) Just below the 40 — 50 m. line the marine formations
are much more distinct and appear to be more recent than
those above. This seems to point to a greater difference in
age than would be deduced from the difference in height.
c) Fossil remains of marine animals (shells etc.) are found
in many places below the 40 — 50 m. line, but nowhere
above it.
This would seem to indicate that: 1) Either the recession
of the sea from the upper marine boundary down to the present
sea-Ievel ceased for a long period, and the coast-line remain-
ed unchanged at this height (40 — 50 m.). 2) Or the sea at