U 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 

 belong 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. 



In the time of these eruptions the ground was also 

 broken up by long fissures which, opening from below, 



