in Norway and in Canada* 7 



wbich have only changed the direction of their strike." Goea 

 Norvegica I, 375, 



The landscape features in the gneiss region vary much. We 

 find in it sometimes tame hills, flat undulating plateaux, in which 

 only the valleys cut into it, have exposed more rugged forms ; 

 but sometimes we find zigzag ridges, sharp peaks, and other 

 remarkable mountain shapes. In the gneiss districts of the 

 south, long-drawn, broad massive mountain ridges are most 

 common, but on the north-west coast, the gneiss rises in rugged 

 and fantastic forms above the surface of the water, in the numer- 

 ous and intricate fiords of that region. 



The mineral deposits of these districts are neither few nor un- 

 interesting. Some of these are worked, and produce silver, copper, 

 cobalt, nickel and iron, while others capable of yielding^ some of 

 these metals or other minerals, remain unwrought or undeveloped. 

 Foremost among the modes of occurrence of metals in this region, 

 must be noticed the so-called fahlbands. These are not exclu- 

 sively confined to the south of the Fields which run north-east- 

 ward across Norway at its broadest part, but it is there, and espe- 

 cially in the district of Buskerud, that they have experienced their 

 greatest development. From a point to the west of Kongsberg, 

 and near the junction with the so-called Telleraarken group, after- 

 wards to be described, north-eastward to Tyrifiord, or to where 

 the gneiss formation in Modum is overlaid by Silurian strata, 

 there occurs a series of parallel zones of rock, having the same 

 strike and dip as the rocks enclosing them, but distinguishable 

 from these by the decomposed appearance and reddish-brown 

 color which they present on the surface. This peculiar appear- 

 ance, to which, according to Bobert, they owe their distinguishing 

 name (from/aAZ or /aid, rotten, as the German miners, who first 

 were employed in their exploration, termed them,) is attributable 

 to the metallic sulphurets which they contain, and especially to 

 iron pyrites ; the ferric oxide and the sulphates produced in the oxi- 

 dation of this being the coloring and decomposing agents. The 

 quantity of metallic sulphurets necessary to produce this color- 

 ing and decomposing etiect, is exceedingly small, and indeed it is 

 sometimes scarcely possible to distinguish them, so finely dissem- 

 inated are they through the mass of the rock constituting the 

 fahlband. The sulphurets most generally present are common and 

 magnetic iron pyrites, and copper pyrites; although blende and 

 galena have both been mentioned as impregnating materials. 



