CONCLUSIONS 51 
a De Geer discussed the late tertiary uplift of Scandinavia and 
Ee pointed out, that in one third the border of the region of upheaval 
; 
is accompanied by basaltic eruptions, which were pressed up by the 
downwarping of the adjacent sea-bottom,! by manner of hydrostatic 
pressure; in sequence the eruption channels were stopped up and the 
pressure transplanted to the main backland resulting in an increasing 
upheaval. In the case of the eastern half of the Arctic plateau, the 
magmatic action beneath the plateau seems to be a more 
active one than was to be expected by simple isostatic 
eadjustment, and perhaps reactions and movements in the 
-asthenosphere, ? as suggested by Ampferer, ? may be the true 
cause of the vertical crust-movements in the case considered. 
In consequence of the statements above, the basalt-marked line, 
which crosses the lower Khatanga, Anabar and Olenek rivers and 
almost points out the boundary between palaeozoic and mesozoic 
_ marine sediments, represents a step fault as described by the writer 
before," but characterized by upheaval of the southern wing, not 
by downwarping of the northern one. The volcanics of this line are 
not yet sufficiently known, but seem to be of a more variegated kind. 
6. CONCLUSIONS. © 
The eastern half of the Arctic basalt plateau is characterized by 
volcanics representing the mixed features of the arctic petrographical 
province; in general, they agree well with the western ones, showing 
almost a constant and uniform composition over great areas, and 
then accidentally acquiring pronounced signs of an alkaline affinity, 
and developing a greater variety of rocks. 
1 G. De Geer, Kontinentale Niveauveränderungen im Norden Europas. Pet. 
Mitt. 1912. IL. 
2 A. Holmes, Radioactivity and the earths thermal history. Geol. Mag. 1916, p. 267. 
3 ©. Ampferer, Uber das Bewegungsbild in Faltengebirgen. Jahrb. geol. Reichs- 
anstalt Wien. 1906. 56, p. 606 et seq. 
4H. Backlund, „La Geographic“ 1. c. 
