322 Reviews — Dr. W. C. Br'dgger — 



different from the present and the margin of the land-ice yet stood 

 before Mjosen and Eandsfjord. 



The upper marine boundary at Ohristiania is about 216 metres 

 (708 feet) above the sea-level, and the maximum of the subsidence 

 occurred when the ice had retreated behind the epiglacial station, 

 and this morainic dam appears to have barred the further extension 

 inland of the sea, for behind it no marine deposits have been met 

 with. The further melting back of the ice took place when the 

 period of elevation had set in, and the valleys then became fresh- 

 water lakes. 



The full extent of the depression of the land at the time of the 

 last ice-sheet is unknown ; that portion of it, from the time of 

 the outer ra to the epiglacial moraine, which can be approximately 

 ascertained, probably represents only the smaller half of the sub- 

 sidence. Shortly before the formation of the outer ra, the land was 

 probably about the same level in relation to the sea as now ; during 

 its deposition the land sank to about 100-125 metres lower than 

 at present, and at this period the older and newer Yoldia-clays and 

 the lower Area-clay were deposited. When the moraines of the 

 inner or second ra were formed, the subsidence reached to 185 m. 

 at Hougen, and at the third morainic station in the Ohristiania valley 

 to about 200 m. ; in front of these moraines the newer Area-clay and 

 the Portlandia-clay were laid down. At the time of the epiglacial 

 moraines, when the subsidence ceased, the land south of Lake 

 Mjosen had sunk about 240 m. (787 feet). 



The climate of the Ohristiania region during the long period of 

 subsidence changed from a high Arctic character to that of a boreal 

 Arctic. At the time of the lower Yoldia-clay the average temperature 



was probably — 6° 9° 0., similar to that of the Kara Sea ; in the 



upper Yoldia-clay period, — 4° 0., like that of the sea round Nova 

 Zembla ; whilst at the time of the upper Area-clay it had risen to 2° 0., 

 similar to that of West Finmark. At the close of the subsidence, 

 during the formation of the epiglacial moraine, the climate probably 

 differed but little from the present one. 



The author proposes to designate the whole interval of the late 

 glacial subsidence, which may well have comprised some thousands 

 of years, the Ohristiania period, and he considers it to correspond 

 with the Ohamplain period of North America. 



IT. The Late Glacial Shell Beds and Clay Deposits formed during the 

 Elevation of the Land. 



The very highest occurrences of late Glacial marine shells in the 

 Ohristiania district were discovered by Mr, P. Oyen in littoral sands 

 and gravels at Grefsen and Arvold, near Ohristiania, at levels of 

 203-208 metres above the sea, only a short distance below the 

 maximum marine margin, which here is 216-218 metres. The 

 shells belong to but few species ; they include Mytilus edidis, Macoma 

 baltica, Mya truncata, Saxicava pholadis, etc. The shells occur for 

 the most part as casts or impressions ; the beds are of a very 

 different character from those at lower levels, and they may probably 



