Geology of Taiiimerfors. — Scdcrho/ni. 215 
clase and orthoclase porphyrytes, which in their original state 
were identical with basalts and andesytes and with modern 
trachytes. A similar porphyritic rock also crosses the phyl- 
lytes in dikes. 
The conglomerates with a crystalline cement are, how- 
ever, the ones which among the Bothnian rocks afford the 
highest interest. They consist of interbedded portions, and 
here they are of greater amount than in any other system 
equally old. 
They can be studied best on the shores of lake Nasijarvi, 
and especially in the little bay of Hormistonlahti, where can be 
seen four vertical layers whose thicknesses are, respectively, 
1-2 metres, 200-300 metres, and 20 metres. They can be fol- 
lowed toward the east for more than 30 kilometres. West- 
ward from Xasijarvi they recur for a distance of 4 kilometres 
in the parish of Ylojarvi, and always at the same geological 
horizon 
The pebliles of this Archean conglomerate are very varia- 
ble as to size, the largest having a diameter of half a metre, 
and the smallest being microscopic. They are generally w-ell 
rounded, and of different forms, according to their petro- 
graphic nature. The greater part consist of different prophy- 
ritic effusions, and of porphyroids, phyllyte and leptyte, all 
these rocks outcropping innnediately to the south of the con- 
glomerate. But there are found also two varieties of granite 
or quartziferous syenyte, and a quartziferous dioryte. 
The cement of the conglomerate is crystalline, but under 
the microscope it shows an originally clastic character. It is 
composed of minute fragments of the same rocks which form 
the pebbles, mixed with fragments of plagioclase, uralitized 
augite, olivine changed to l:)iotite, etc., and of secondary min- 
erals, especially of feldspar, quartz and biotite. The beds of 
conglomerate alternate with a dark-green schist very rich in 
uralite, which is a metamor])hic tuff of a basic effusive rock. 
-Ml these beds are vertical. 
X'orth from these beds of conglomerate are found, on 
]^oint Kameeniemi, a new conglon.cratic bed. with a thick- 
ness of 20 metres. If this bed. as well as the tuffs and phyllytes 
that appear toward the north, were originally superposed con- 
tormabl}' u])on the rocks which outcrop to the south from 
