320 Reviews— Dr. W. C. Brbgger— 



wide areas to be accounted for by ice-transport from the shallow- 

 water localities round the coast, and on the supposition that they are 

 now in the spots where they lived, it would be needful to postulate 

 a former elevation of the sea-bottom to the extent of 800-1400 

 fathoms. Brogger considers that during the great glaciation the 

 land may have been elevated perhaps to 2,600 metres above its 

 present level, and this would furnish an explanation of the formation 

 of the deep fjords, and of the movement of the land-ice from the 

 Scandinavian highlands to the central European plain during the 

 great glaciation. 



The banks of dead littoral shells forming a continental platform 

 along the west coast of Norway, at depths of 100-300 metres, are 

 compared with the sunken shell banks of Eockall and those off the 

 Faroe Islands, and they are considered by the author to point to 

 a widespread elevation of the sea-bottom amounting to 100-300 

 metres in the last interglaoial period, which may have continued 

 during the last glaciation of Norway. 



In the lower part of the valley of the Glommen, near 

 Frederikstad, the lower Yoldia-clay is overlaid by another clay not 

 more than 1-2 metres in thickness, containing nearly the same fauna 

 as the lower bed, but the forms are smaller, and some new species 

 appear, for example Yoldia hyperhorea, Loven, which lives at 

 greater depths than P. (Yoldia) arctica. These facts show that the 

 upper Yoldia-clay was formed at greater depths than the lower, and 

 that the sinking of the land was continuous. 



The upper Yoldia-clay gradually passes upwards into another 

 deposit, only a few metres in thickness, in which most of the species 

 are new, whilst Portlandia arctica, the characteristic shell of the 

 Yoldia-clays, has quite disappeared. Amongst the principal forms 

 are Area glacialis, Gray, and Portlandia lenticula, Fabr., and from 

 the first of these the beds are named Area-clays. They contain 

 about twenty species of mollusca, all high Arctic forms, which now live 

 at considerable depths in the Polar Sea, and it is probable the beds 

 were laid down at depths of 80-100 metres. Like the Yoldia-clays, 

 the lower Area-clays are only found outside the ra, and as some of 

 them are now 25-40 metres above the sea-level, it follows that the 

 land, at the closing period of the outer ra, was 100-125 metres 

 lower than at present. 



After the deposition of the lower Area-clays on the areas beyond 

 the outer ra, a somewhat rapid change in the rate of melting of 

 the glacier took place, which resulted in the retreat of the ice 

 northwards up the Christiania fjord for a distance of 20-25 

 kilometres, where another pause was made which resulted in the 

 formation of the Svelvik terminal moraine, or inner ra. In 

 structure this resembles the outer ra : it was laid down beneath 

 the sea ; its present height is 150-190 metres above the sea-level. It 

 has a length of about 2 kilom., and the breadth of its base is 1| kilom. 

 Two-thirds of its materials consist of sand ; the remainder are pebbly 

 gravels of granite, hornblende schist, and quartzite, with a few 

 angular striated boulders. 



