174 Reviews — Glacial Uplift in Norway. 



D'ORBIGNY, 1851-4 ; " Bryozoaires ; Paleontologiefrancaise, Terrains cretaces," 



vol. v. 

 D'Oebigny, 1852 2 ; " Cours elementaire de Paleontologie et de Geologie 



stratigraphiques," vol. ii. 

 "VON Beuss, 1846; " Die Versteinerungen der bohmischen Kreideformation," 



part 2. 

 Bomer, 1840 ; " Die Versteinerungen des Norddeutschen Kreidegebirges." 

 Smitt, 1868; " Kritisk forteckning ofver Skandinaviens Hafs-Bryozoer " ; 



Of. kongl. Vet. forhandl. for 1867, pp. 279-429. 

 Smitt, 1873 ; " Floridan Bryozoa collected by Count L. F. de Pourtales " ; 



Kongl. Svensk. Vet. Hand. ; new. series, vol. xi, No. 4. 

 Verrill, 1879 ; ' ' Contributions to tbe Natural History of Arc,tic America, 



Molluscoids" ; Bull. United States Nat. Mus., No. 15, pp. 147-150. 

 Vine, 1893; "Beport of the Committee . . . appointed for the completion 



of a report on the Cretaceous Polyzoa " ; Bep. Brit. Assoc, 1892, 



pp. 301-337. 



ZRIEVIE^WS. 



I. — Irregularities in the Post- Glacial Uplift op Norway. 



BY measuring the present heights of old sea-beaches the Scandi- 

 navian geologists have been able to work out the salient features 

 of the tilt their country has acquired during its rise in Post-Glacial 

 times. To demonstrate the amount and character of the uplift since 

 any particular period, it is first necessary to distinguish the beach, 

 formed at that period, which is itself often a matter of considerable 

 difficulty owing to the presence of other beaches, and then to measure 

 the various levels at which it now occurs. These determinations are 

 marked on the map, and from them lines — the isobases — are drawn 

 such that for any points on one line the present height of the beach, 

 is the same, the lines being drawn for convenient and constant 

 differences of level. Thus the character and degree of uplift are 

 seen, at a glance, the isobases lying closer together where the tilt is 

 greater and farther apart where it is less. These maps are usually 

 drawn on a small scale, and the isobases appear as smooth parallel 

 lines with a fairly constant distance between, indicating that the 

 country has yielded to the forces of upheaval as one homogeneous mass. 

 Eecently, by determining the heights of old beaches with great 

 care and plotting on a large scale map, Holmsen has found that the 

 isobases in some districts swing right out of their normal course, 

 proving minute but unmistakable inequalities of uplift. 1 The beaches 

 of former ice-dammed inland lakes are better adapted for this accurate 

 work than those marking ancient sea-shores in the coastal regions, 

 because they are in a more complete state of preservation. This is to 

 be expected when it is remembered that the sea-level sank little by 

 little, so that there is not only a risk of confusing the various coast 

 beaches, but they have often been mutilated and sometimes obliterated 

 by the waves of the gradually falling sea surface. As the glacial 

 lakes were suddenly drained, no such force has operated to mar their 

 beaches, the levels of which can be determined with great accuracy. 



1 " Om Strandlinj ernes FaldomkringGabbroomraader'' : Gunnar Holmsen, 

 Norsk Geologisk Tidsskrift, Bd. iv, H. i, pp. 7-20, 1916. 



