102 M. DE HoFF on some basaltic 



mica, flattened nodules of clay are observable In it, which 

 belong to the variegated sandstone formation* (buiiter sand-, 

 stein.) Approaching the basalt, the sandstone becomes yel- 

 lowish, loses its granular texture, and acquires an earthy 

 and dull appearance. The horizontal fissures disappear, and 

 are replaced by beds of brown clay some inches thick; and 

 a number of clefts and fissures are seen in it. 



The wedge of basalt, which is only from three to four 

 metres [about 10 to 13 feet] thick at the summit of the 

 mountain, becomes thicker as it descends. On the east 

 side it is separated from the sandstone by an open cleft, 

 as much as a decimetre [about 4 in.] wide, and the sand- 

 stone is, on the side of the cleft, covered by a vertical lining, 

 from five to six millimetres [about | in.] thick, formed of 

 an argillaceous sand of a greenish yellow, penetrated by 

 dendrites. Towards the west the basalt is in immediate 

 contact with the sandstone. An open and almost vertical 

 cleft is observable in the interior of the basaltic mass, di- 

 viding it into two unequal parts, the nature of which is not 

 the same ; there are moreover a multitude of little fissures 

 irregularly disposed. Towards its western end, the basaltic 

 mass forms a hook, or almost horizontal branch, which pener 

 trates some metres into the sandstone. The fissures of this 

 portion are almost all arched, and nearly parallel to the 

 curve forming the hook. 



The basaltic mass contains, in its upper part, the remains 

 of sandstone beds disposed horizontally, and divided also 

 by the vertical cleft of which we have spoken above. It 

 contains moreover not only common basalt, but, 1st, basalt 

 in balls, in an aggregate that in some respects resembles 

 greywacke, which is penetrated by calcareous veins, and 

 contains small crystals of oxidulated iron; 2ndly, a basaltic 

 amygdaloid (variolite), containing cavities filled by the usual 

 substances in such cases, but also enclosing fragments of 

 sandstone ; 3dly, the basaltic hornstone of Messrs. Sartorius 

 and Gorwitz ; 4thly, the lave lithoide petrosiiiceuse of 

 Dolomieu; 5thly, the blistered lava (lave boursoufiee) of 



* NevT red sandstone formation. (Trans.) 



