INTRODUCTION 7 
the Pacific borders. Four sub-provinces are distinguishable in this 
region, namely the British area, the titaniferous belt, the area of 
Jan Mayen and younger rocks of northwestern Spitsbergen, and 
the area of older rocks of Spitsbergen, the basalts of Franz Joseph 
Land and those of the mouth the Yenisei river with the plateau 
basalts of the Yenisei-Tunguska region. — The dimensions of the 
fourth sub-province seem to be much too great compared with the 
others, and much too variegated by geological processes acting 
upon it during the volcanic aera of its development to be a simple 
one; this probable exaggeration in dimensions is caused perhaps 
by want of knowledge of details upon the North-Siberian plateau. 
The contributions to the knowledge of the basalts of the Yenisei- 
mouth, ! cited by Holmes, are too insignificant to conclude upon 
the whole eastern region, and the earlier descriptions of some 
Russian Authors (Polenov, Lavrsky), which embrace great parts of 
the Lower Tunguska- and Vilui-river basins, are too indefinite and 
too inanimate and the bulk analyses too incomplete to give an 
idea either of the character of these basaltic rocks or of their 
geological position. And finally, it may not be forgotten that the 
taimyrite, this remarkable nosean- and glassbearing trachytic rock, 
described by Khrustchoff,? probably is of late mezozoic or early 
tertiary age and belongs to the plateau; no analysis is given of 
this rock and no definite locality (,erratic from the Taimyr-Land‘) 
named, but an association with the basalts is more than sure. 
A glance at the distribution of these basalts, given by Suess, ? 
begins from the south of the amphitheatre of Irkutsk, from Northern 
Mongolia and the Alps of Tunkinsk and then goes down the river 
1 H. Backlund, Krist. Gest. v. d. Nordküste Sibiriens I. Mem. Ac. Sei. St. Pé- 
tersbourg 1910. XXI. N:o 6. 
2 K. v. Khrustchoff, cited by H. Rosenbusch, Mikrosk. Physiogr. II. 2. 1908 
p. 925. 
3 S. Suess, La face de la terre, trad. par E. de Margerie, III. 2. pp. 942—956, 
peculiarly p. 948. 
