170 SCALPA. GEOLOGY. 



substance through which it passes. Another variety of 

 the gneiss occurring in this singular spot is also worthy 

 of notice. It has the character of graywacke, consisting 

 of an argillaceous base with imbedded grains of quartz 

 and felspar. I have already shown on different occasions 

 that micaceous schist as well as talcaceous and chlorite 

 schist form beds in gneiss, and that even clay slate does 

 the same : in this instance the rule may also be said to 

 extend to graywacke. 



Trap veins are not wanting in this island, since a very 

 large one of a laminar structure is found in a vertical 

 position crossing the gneiss. 



Lastly, I may add to this account that small particles 

 of chromat of iron are found dispersed in the serpentined 



* When in this island, a shoal of bottled-nosed whales amounting 

 to some hundreds had been forced ashore and taken. They are very 

 abundant in this sea in the autumnal season, following the herrings. 

 They appear to pay that implicit obedience to a leader which is so 

 remarkable among land animals, in the deer, and in the duck tribes. 

 By this they are taken, since, when the head fish of the shoal has been 

 driven on shore by the boats, the whole follow until they take the ground ; 

 when their retreat is easily cut off. 



