Rit (Vísindafélag Íslendinga) - 01.06.1923, Side 117

Rit (Vísindafélag Íslendinga) - 01.06.1923, Side 117
113 (Nos. 25 — 27) were probably formed. They indicate a similar sea temperature to that now found on the west coast of Greenland (Sipho togatus, Astarte Banksii, var. Warhami etc.). The coast-line then was possibly abt. 50 m. higher than at present. When these strata began to be formed near Akranes, the glaciers still covered the low-lying ground in the Borgarfjörður district, so that it was not possible for strata with similar fauna to be deposited there at that time. At a later period the glaciers receded from the low-lying districts of Borgarfjörður- to the valleys, but they probably remained stationary for a long time at the entrances to the valleys and piled there up terminal moraines. As the glaciers melted, tlje land subsided, until the highest coast-line was reached (abt. 80 — 100 m. above present sea-Ievel). 2. There is no doubt that the coast-line remained stat- ionary for a considerable period at the highest limit (No. 2 in Fig. 8), for the sea has there in many places formed broad surf-ledges in the solid rock ánd extensive terraces; the latter especially at the entrances to the present valleys. At the same time the ice-boarder receded from the valleys, at any rate to some extent, so that the sea was able to íorm marine terraces there. 3. Subsecjuently the land began to rise, so that the sea- board receded from the highest limits, probably withoul interruption, down to 40-50 m. above present sea-level (No. 3 in Fig. 8). There is no doubt that some of the strata in the marine terraces in Borgarfjörður were deposited durlng the periods mentioned, but it is not easy to distinguish between them and other strata which have been deposited since. None of the shell strata that were found at Borgarfjörður can be stated with certainty to belong to these periods, except perhaps the shell-bearing gravel and clay strata, lowest down in some of the marine terraces (e. g. Neðranes). It is nevertheless more probable that they are of a later date. 4. Either the coast-line remained stationary for a long time at the 40-50 m. limit, or else it first receded con- 8
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Rit (Vísindafélag Íslendinga)

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