PHYSICAL CONDITIONS— POSTGLACIAL. 515 



sweep over them, forbidding the growth of all arboreal vegeta- 

 tion. Now, as there can be no doubt that the " buried trees " of 

 the Fseroe Islands belong approximately to the same date as 

 those of our own islands and North- western Europe, it seems 

 impossible to resist the conclusion that the climate of those 

 regions in the postglacial period must have been, for some time 

 at least, considerably more genial than it is now. 



This conclusion derives strong support from the very inter- 

 esting researches of Mr. Axel Blytt into the cause of the pre- 

 sent distribution of plants in Norway. He points out that in 

 the coast regions of the province of Christiansand and Smaalene 

 there are found a number of species which are either absent or 

 very seldom found in other parts of the country. 1 Amongst 

 these are some, he says, which are very rare, and known to grow 

 in only one place in Norway. The majority of this group of 

 coast-plants occur again in the south of Sweden, but they are 

 absent in the Christianiafjord. Their distribution out of Scandi- 

 navia is chiefly in the maritime districts of Western and South- 

 ern Europe, down to the coast of Portugal and the Mediterranean ; 

 while in Scandinavia itself some are confined to the west coast 

 of Norway. 2 The deep submarine trough which runs round 

 the southern coast of Norway forbids, according to Blytt, the 

 supposition that these plants could have entered Scandinavia 

 directly from the old land-surface that now lies drowned in the 

 North Sea; during postglacial times that deep trough would 

 exist as a long and broad fiord. 3 Blytt concludes, therefore, 



1 Such as Qiiercus sessiliflora, Teucrium scorodonia, Jasione montana, Hcdera 

 helix, Rosa rubiginosa, Rubus thyrsoideus, R. Lindebergii, R. Radula, R. corylifolius, 

 R. Wahlbergii, Cladium mariscus, Heleocharis multicaidis, Petasites alba, Pulicaria 

 dysenterica, Atriplex farinosa, Filago minima, Gentiana pneumonanthe, Ajuga 

 reptans, Berula angustifolia, Epilobium tetragonum, Agrimonia odorata, Tri- 

 folium procicmbens, T. minus, Vicia cassubica, Coronilla emerus, etc. 



2 Amongst these Blytt mentions Asplenium marinum, Hymenophyllum Wil- 

 soni, Carex binervis, Scilla verna, Erica cinerea, Conopodium denudatum, Meum 

 athamanticum, Rosa involuta. Essay on the Immigration of the Nonvegian Flora, 

 etc., pp. 27, 28. 



3 It is possible, however, that when the land reached its greatest extent, even 

 that deep trough may have been vacated by the sea. But the soundings show 

 that with such an elevation of the sea-bottom a long deep lake would occupy a 



