26 



remaining part of the group of islands, i. e. all the Islands with tlie 

 exception of a part of Sydero and Myggenæs. The dolerite is a 

 coarsely crystalline basalt in which crystal of plagioclase is distinctly 

 visible; it is usually porphyritic. 



The beds of coal as well as those of anamesite and dolerite 

 are separated by tuff-layers of various colours, chiefly red or blue- 

 grey; as the tuff is easily decomposed , small, nearly horizontal 

 partings answering to the tufT-layers are generally distinctly visible 

 on the vertical faces of rocks (Fig. 14). 



With regard to the age of the igneous rocks of the Færoes, 

 ver}^ liltle is known. The coal-bearing strata contain remains of 

 stems and branches, but plant-remains fit for determination have 

 not as yet been found. Still we are justified in arriving at a con- 

 clusion as to their age by the faet that the perfectly analogous Ice- 

 landic formations are Tertiary and must be referred to the Miocene 

 period of that era on account of the fossil piants (the so-called 

 »Surtarbrand«) which are met with. 



Of later origin than the general extent of basalt are the scattered 

 slieets and veins of intrusive basalt, which are intruded among the 

 beds. This intrusive basalt which occurs here and there is close 

 and dark. At a few piaces, especially at Frodebo on Sydero, it 

 appears in beautiful specimens ofisolated prismatic columns (Fig. 15). 



Ice Age and its Actions. Like most of the other northern 

 countries, the Færoes have had their Ice age, distinct traces of which 

 can be found on the islands. For the purpose of studying these 

 traces, a minute investigation of the islands was made by the 

 geologists Geikie and Hellami. The usual characteristics of glaciation 

 are striæ, roches moutonnées, moraines and rock-basins. 



As basalt-rocks are rather liable to decomposition, striated faces 

 are rarely met with, but some instances occur in piaces where the 

 rock-surface has been protected by a coating of earth so that the 

 atmosphere has not been able to aet upon it. Fine striated faces 

 are said to exist at Thorshavn on Stromo, at Ej de on Ostero and 

 at Sands on Sando, but they are also found at other piaces, and 

 further investigations will doubtless bring to light many more. The 

 peculiarity of these striæ is that at each place they seem to have 

 a different direction, a faet which will be explained later on. 



The second glacial characteristic, roches moutonnées, is much 

 more common on the islands; everywhere in the valleys and 

 on the lower hills are seen these rounded formations, due 



