B84 SCIENTIFIC NiWS. 



Minerilbgyof "finje past employed in examining the mineralogy of those 

 the shetlaiid remote islands, communicated to the Society an interesting 

 account of the geognostic relations of the rocks in the 

 islands of Unst and Papa Stour; in the course of which he 

 gave answers to the queries formerly published regarding 

 the serpentine and sandstone of Shetland. After a general 

 account of the position, extent and external appearance of 

 ' the island of Unst, he next described the different rocks of 



which it is composed, in the order of their relative antiqui- 

 ty, and remarked, that their general direction is from S. W. 

 to N. E* The rocks are gneiss, mica-slate, clay-slate, 

 limestone, hornblende-rock, potstone, and serpentine. — 

 The gneiss in some places appeared to alternate with the 

 oldest mica.slate, and in others to contain beds of horn- 

 blende-rock. The inica-sla(e, which is the most abundant 

 rock in the island, is traversed by numerous contempora- 

 neous veins of quartz, and also of feldspar, and passes dis- 

 tinctly into clay-slate. It contains beds of hornblende-rock 

 and of limestone. The clay-slate occurs but sparingly in 

 this island. The potstone usually accompanies the serpen- 

 tine. The serpcjitine occurs in great abundance, in beds, 

 in the oldest clay-slate and newest mica-slate, and hence 

 must be referred to the oldest or first serpentine formation 

 of Werner. Mr. Fleming is also inclined to believe, that 

 the serpentine of tlic neighbouring island of Fetlar belongs 

 to the same formation. The island of Papa Stour, situate 

 on the west coast of the Mainland, (as the largest of the 

 islands is called), contains no primitive rocks ; on the con- 

 trary, it appears to be entirely composed of floetz rocks. 

 These are, conglomerate, greenstone, claystone, porphy- 

 ritic stone, hornstone, and sandstone. The sandstone, as 

 appears from observations made in this island and other 

 parts of Shetland, would seem to belong to the oldest coal- 

 formation. The claystone, conglomerate, porphyritic 

 stone, greenstone, and hornstone (probably clinkstone) 

 rest on the sandstone. lu sonve places Mr. Fleming ob- 

 served the greenstone alternating with the sandstone, hence 

 he properly concludes, that they belong to the same forma- 

 tion. In no place, however, did he observe any of the 

 other rocks alternating with the sandstone; and therefore 

 the formation to which they belong remains still somewhat 

 problematical. 



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