170 ROLLIN T. CHAMBERLIN 
among either the Highlands on the one hand or the Silurian Uplands 
on the other.* 
In Scandinavia the deformed igneous masses resting upon the 
Cambro-Silurian sedimentaries in the Caledonian mountain belt 
have been regarded by Térnebohm as portions of the Archean 
brought from the west by the overthrusting process.” If so, 
contemporaneous intrusions played little part in the overthrust 
sheets. According to Holtedahl, however, the gneisses are to be 
regarded as highly pressed younger intrusive masses which, during 
the deformation, broke forth and moved under enormous pressure 
from the central belt outward. If in truth these be intrusions 
related to the Caledonian diastrophism, they are in any case more 
characteristic of the central belt than of the outer borders. 
Among the intensely deformed Cenozoic Alps intrusions of 
Tertiary age are practically wanting in the central and northern 
ranges which together make up the region of the nappes de charriage, 
or great overthrust sheets. But in the root region of the Lepontine 
sheet and the Dinaric zone on the south side of the Alps, from which 
the overthrust masses are thought to have come, the last phase 
of strong mountain-building was characterized at various points 
by intrusions of a granitic nature. Steimmann has already em- 
phasized this contrast between the region of the roots and the 
region of the sheets. 
In addition, it is of course to be noted that quite outside of the 
true mountainous belt, particularly opposite the inner curves of 
the arcuate chain (in Hungary, Italy, etc.), volcanic phenomena 
attained considerable prominence.’ But the more or less con- 
temporaneous extra-montane vulcanism, though related to the 
mountain-building stresses, is not a part of this discussion. 
Sir Archibald Geikie, Ancient Volcanoes of Great Britain, Vol. I (1897), p. 272. 
2 A. E. Térnebohm, “‘Grunddragen af det Centrala Skandinaviens Berbyggnad,”’ 
Kongl. Svenska Vet.-Akad. Handl., Vol. XXVIII (Stockholm, 1896), pp. 1-210. 
3 Olaf Holtedahl, ‘‘Paleogeography and Diastrophism in the Atlantic-Arctic . 
Region during Paleozoic Time,” Am. Jour. Sci., Vol. XLIX (1920), pp. 1-25. 
4G. Steinmann, “Die Bedeutung der jiingeren Granite in den Alpen,” Hawpt- 
versammlung der geol. Vereinigung, Frankfort (1913), pp. 1-4. 
5 Marcel Bertrand, ‘‘Sur la distribution géographique des roches éruptives en 
Europe,” Bull. soc. géol. de France, 3° sér., Vol. XVI (1887-88), pp. 573-617; Alfred 
Harker, op. cit., pp. 20-22, 42. 
