Geology of TaiiiDierfors. — Sedcrliobn. 2 1 7 
This granite also shows a zone of endogenous contact, in the 
form of a structure at once porphyritic and evidently micro- 
pegmatitic, although in part concealed by the metamorphism 
which the rock has suffered since consolidation. 
The granite contains, at several points, elongated bands 
of schists, and everywhere very numerous fragments. These 
inclosures are in general strongly granitized, and in that case 
they have the structure of a dike gneiss ("gneiss a filons"), 
or of a dioryte. But these enclosures show also, here and 
there, the structure and the mineralogic composition of the 
schists of Tammerfors, and contain sometimes undoubted 
pebbles, which are incontestable proof of the sedimentary 
origin of the enclosed fragments. Quite often, as for exam- 
ple, north of Teiskola, these enclosures have an aspect of a 
true dioryte, though of a variable structure. 
The schists w^hich outcrop in the parishes of Suodenniemi 
and Lavia at the west of Tammerfors are in part more meta- 
morphosed than those of which we have just spoken. Phyllyte 
is here often replaced by mica schist which only differs very 
little in its petrographic composition from the mica schists of 
the underlying formation. Here also is a conglomerate which 
has almost the aspect of a gneiss spotted with amphibole. At 
Harju, in the parish of Suodenniemi, is another very interest- 
ing conglomerate, on account of its almost gneissic structure. 
(3n the surface which is attacked by the atmosphere, the con- 
tours of the pebbles and their rounded forms appear very dis- 
tinctly, but in the hand specimens, and especially in thin sec- 
tions, their limits are confused in consequence of the presence 
of numerous secondary minerals. Everywhere one can recog- 
nize among the pebbles representatives of some of the rocks 
that occur in the underlying gneiss, among others of the 
"gneiss of Lavia." This porphyroidal schistose rock recalls, 
when it is well preserved, a tuff or a porphyritic effusive rock 
which by a profound nu'tamorphism has been made to take 
the aspect of a gneiss. 
It is very interesting to see here the most positive demon- 
stration of a discordance between the Bothnian schists of 
Lavia and the mica schists of the underlying formation which 
possess almostthc same petrographic characters. At Lavia, in- 
ileed, can be seen the clear contact of the granite catting the 
