174 MINERALOGICAL ACCOUNT 



common jasper ; and the amygdaloid contains 

 veins of red haematite. 



From the above statement of facts, it does not 

 seem improper to conclude, that all the beds of 

 rock in Papa Stour, belong to one and the same 

 formation. Besides the support which this con- 

 clusion receives from the account of the relative 

 position of the different rocks as mentioned above, 

 it is likewise countenanced by the occurrence 

 of veins in the different beds, filled with si- 

 milar mineral substances ; and particularly, from 

 the circumstance of those slips, or dislocations 

 of the strata, whereby the beds are depressed, 

 and which affect the beds of sandstone, compact- 

 felspar, and porphyry-slate, and the other rocks 

 in the island, all in a similar manner. This pro- 

 bably would not have been the case if they had 

 belonged to separate formations. The fissures, 

 formed in consequence of these slips, are fil- 

 led with decomposed portions of the surrounding 

 strata. 



Since the conclusion — that the rocks of Papa 

 Stour belong to one and the same formation,— ap- 

 pears supported by such proof, it still remains to be 

 determined, to which of the formations, in the 

 class of floetz-rocks, they ought to be referred. 



The sandstone of Papa Stour, is exactly similar 

 to the sandstone in the islands of Foulah and 

 Bressay. In the former of these islands, the sand- 

 stone is accompanied with bituminous-shale and 

 clay-ironstone, and rests on gneiss as the funda- 



