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acterized by Populus tremula, and this again by a Pinus sylvestris flora.
Above the layer with Pinus comes a new one with oak and finally the surface stratum with recent forest trees. Now in the peats of deuteroglaciated Norway and Sweden we always find the oak layer on the bottom (with a layer of pine and birch above), which shows, without doubt, that the preceding vegetations in Denmark and Scania must be interglacial. To judge from the aspen and pine forests it might be concluded that the interglacial climate in Scandinavia was somewhat colder than the present, but the melting of the ice may have required a higher temperature and the fossils from layers between the two bottom moraines in the Baltic countries bear a rather southern stamp.
We come to more reliable ground when we advance to the last great glaciation in the deuteroglacial period. Again the snow gathered on the high mountain plateaus, again glaciers pushed forward towards the lower ground accompanied by a severe climate. But the glaciers this time were met almost at the watershed by the deep proteroglacial fjords which necessarily must put an end to their advance westward. The continuous western ice margin could not reach beyond the fjord heads. To the east, however, the way was free for the growing inland ice. The consequence of this was that the ice sheet divide crept eastwards and reached a line up to 130 kilometers southeast of the land watershed. Here at last the resistance to the glacier motion was alike on both sides of it. We therefore find the boulders in deuteroglacial time—in contrast to the distribution in proteroglacial time—transported across the watershed from lower ground in southeastern central parts up hundreds of meters to the divide and borne on as far west as the deuteroglacial ice and its icebergs went.
To the west we find the ice margin determinated by the fjords, to the east it pushed forward out to the coast line by Skagerak. We find its margin, as in the case of the deuteroglacial ice in North America, marked by a long terminal moraine—raerne—from Arendal to the Kristiania fjord and thence to southeastern Sweden.