340 The American Geologist. November, imi 
schists and the porphyritic granite of Sederhohn's t>lder Arehean or 
pre-Bothian formations. These rocks cover a large ai-ea to the south of 
Taiumersfors and extend in an east and west line from lake Paijanne to 
the gulf of Bothnia. The mica-schist is folded but at the localities vis- 
ited does not show a high degree of metamorphism. 
At Mauri occurs a fine exposure of an interesting metamorphicrock, 
called by Sederholm leptite. This is a fine-grained gneissic conglomer- 
ate, rich in feldspar and poor in mica. The mica that is present is 
largely muscovite. The rock is of a reddish color and while quite gneis- 
sic, its original conglomeratic character is by no means obscured. A 
lamination, which has been considered original erossbedding, is some- 
times marked. This leptite is referred to the Bothnian formation. 
On the second day the imrty coasted in large open boats along the 
east shore of the picturesque lake Nasijarvi. The first landing was made 
at the paint (south of ilitoniemi) where Dr. Sederholm has found re- 
markable "Arehean fossils:" in the '■'Bothnian phyllites.'* These slaty 
phyllitesare rich in carbon and plainly of setUmentary origin. They 
bear some cui'ious slipper- shaped markings. The impressions are 3- 
10cm. in length and 2-3ciu in width and art^ (jutlinedby a depressed rim 
(weathered out) of an anthracitic character, app-roaching graphite. 
They lie in bands approximately parallel to the slates in which they 
occur. Sederhohn is inclined to consider them of organic and probably 
of vegetable origin. 
Farther to the north, finely exposed on sonte of the islands of the lake 
and also upon the east shore, is the conglomerate s<;hist (Bothnian 
age) which bears such plain evidence of clastic origin^ 
This conglomerate, together with other ancient sediments. Seder- 
holm separates by two imjxjrtant formations and three great discord- 
ances from the Cambrian, and asks if there may not be in the under- 
lying crystalline complex genuine sediments, which ai-e of api.proximately 
the same age as the granites and gneisses of the complex. 
In answering the question afili'matively he does niot accept the dis- 
tinction which has been made in America between the Archaean and 
Algonkian. 
This elastic schist is. of a conspicuously conglomseratie character, 
with vertical bedding (?) and a thickness in same cases of 300 m. 
The pebbles vai-y in size from 5 m. in diameter to microscopic dimen- 
sions. They are oval in form and petrographically are porphyrite,. 
porphyroid, phyllite, leptite and granite fragmentsv The cement is 
crystalline but composed of clastic fragments of the same material as 
the pebbles, associated with secondary minerals (feldspar, quartz and: 
biotite). Interbedded with this conglom-erate ai-e basic tuffs and 
porphyroids. 
The most interesting observations of the thh-d day wei-e made in the- 
railway cuts south of Orivesi. Here occur contacts- between the 
Tammersfors schists (Bothnian) and two granites. The granites are 
distinguished only by the occurrence of porphyritic crystals in the one 
case and theii- absence in the other. The discussion turned on the com- 
