6 Mr Theodore Kjerulf on the Phenomena 
has remarked fine examples of weather sides at a distance, 
we have good ground for distrusting his conclusions. 
3. As to the marking of the arrows on the maps they 
often convey a false impression. The striations do indeed 
run towards valleys, and in a general way follow the lines 
of the valleys; but even the mountain plateaus have their 
valleys, which do not appear in maps of the small scale 
ordinarily used ; were these marked, we should at once see 
that the friction has followed the valleys. 
4, Finally, there is this to be laid down as a first principle, 
that the mere study of the phenomena and direction by com- 
pass of the scratches, and of the often quite independent 
boulders, is not sufficient to determine whether the agent 
which produced them was a stream or a glacier. Brogniart 
has called the striations the wheel-ruts of the phenomenon ; 
but we have kept too much to the ruts, and forgotten the 
carriage and team. The loose masses, which owed their 
presence to this phenomenon, have passed unobserved. It is 
these we must study, if we are to understand the pheno- 
mena of friction; and it is as a name for these, the clay- 
sand and masses of debris connected with the phenomena 
of friction, that the term, ‘“‘ the Glacial Formation” has been 
introduced. And in fact there is more to be learned from 
the study of a single example of the glacial phenomena, in 
which all the various members of the formation are ex- 
hibited, than from thousands of scratches traced by the 
compass. | 
I proceed, therefore, to examine the glacial formation in 
detail as it presents itself in the district around Christiania. 
The glacial formation includes masses of debris, blocks of 
stone, varieties of clay, and layers of sand. The term gla- 
cial is applied to it, partly because the oldest fossil shells 
found in it are of arctic species, and partly because the 
debris, the scratched rock surfaces and the boulders, con- 
nected as these are together, indicate that when they were 
produced the whole country was covered with ice. The 
entire formation may be divided into an earlier and a later 
group, of which the earlier alone is strictly glacial; but 
since the material of which the later group is composed 
was also originally glacial, and since the two groups are 
4 
