2i8 The Anierican Geologist. April, isos 
schists of the.!4"iieissictcrranc with the schists of Lavia. In the 
contact zone the g'raiiite presents the character of a breccia 
which near the schists, assumes the aspect of a basal con- 
glomerate. Evidently the surface of the granite was disinte- 
grated by atmospheric action before the deposition of the sedi- 
ments which in a metamorphic condition, form now the schists 
of Lavia and of Tammerfors. The same phenomenon is re- 
peated at several places in the same region, though in 
conditions less typical. 
The mass of the schists in the west of Finland formed, like 
the schists of the region of Tammerfors, in the interval be- 
tween the two great Archean epochs of granitic irruption in 
those countries, has received the name of the "Bothnian for- 
mations." To this series of rocks belong also the uralitic 
porphyrytes of Tammela and of Kalvola at the west of Taves- 
tehus. and of Pellinge near Borgo. The effusive character 
of those Archean rocks, accompanied by tuffs, cannot be 
mistaken. Further one can also refer here probably the schists 
which outcrop at Ylivieska, in the government of Uleaborg, 
and perhaps also several formations in northern Sweden. All 
these schists, whose layers are always almost vertical, abound 
in intercalations of conglomerates. 
Again, in the neighboring portions of the coast of the gulf 
of F'inland, where the land is composed of Archean rocks of a 
different age, dislocated at the same epoch and intimately pen- 
etrated by post-Bothnian granites, can be found, at several 
places, debris of Bothnian rocks the original composition of 
which is sufficiently preserved to be recognized. 
All this country having thus undergone intense disloca- 
tions at an epoch later than the deposition of the Bothnian 
beds, it is not possible to doubt their pre-Cambrian age, es- 
pecially if one takes into consideration that the beds of Cam- 
brian and Silurian rocks of Esthonia, on the opposite shore, 
south of the same gulf, are almost horizontal. It is to be re- 
marked also that the pre-Cambrian sandstones of Bjorneborg 
and of Kauhajoki, and the granito-porphyritic rocks called 
"rapakivi" which occur in very extensive "massifs" in the 
south of Finland, do not show any sign of metamorphism. 
The pre-Cambrian age of the rocks mentioned being 
proved by the fact that they have been recognized in the form 
