n2 FORESTRY OF NORWAY. 
this is a second layer designated the trinucleus and chas- 
moss limestone, and a third called the layer of gray lime- 
stone. These are all comprised in the lower silurian 
formations, and above these are three superior silurian. 
formations belonging to a later period. ; 
Rarely are all these layers found superimposed in a 
complete series. Ordinarily there are found some parts of 
the series exposed in steep stratifications, which, being 
traced, are seen to belong to great corrugations which 
have: been produced by a powerful compression of , the 
whole. system of layers, by means of a stupendous force 
accompanying the appearance of the great later irruptive 
masses. Subsequently, the projecting portions of the cor- 
rugations having been worn away, their remains appear as 
dislocated stratifications. 
Above the upper silurian layers, with their abundant 
fossils, are great beds of red argilaceous schists, red and 
gray coloured. sandstones, and conglomerate, supposed to 
beleng to the Devonian formation or old red sandstone ; 
but no trace of fossils has yet been found in them. Men- 
tion must also be made of a field of sandstone of uncertain 
age, but apparently still older. 
Subsequently to the period of the first appearance of 
swarming animal organisms in the middle of the silurian 
period, and repeated perhaps long after the Devonian 
epoch, we see that anew great eruptive masses of different 
kinds have been thrown up from below, sometimes in lines 
straight as if drawn by a cord, sometimes in small isolated 
spots, sometimes over great areas, and sometimes as a 
stream flowing over the earlier formed layers. 
Some of the granite of this region is, as is the case in 
the Grefsenaes, near Christiania, very easily wrought in. 
long comparatively narrow pieces ; and being susceptible 
of a very fine polish, it is exploited on a great scale for. all 
kinds: of, building purposes: stairs, kerbstones, sockets, 
pillars, tombstones, &c. i 
In the time of these eruptions the ground was also 
broken up by long: fissures which, opening from: below}. 
