MINERALOGY. 363 



montory on the east coast of Noss Isle, composed of sand- Mineralogy of 

 stone of different hues, hollowed out below into innu- Shetland, 

 merable caverns, the retreat of myriads of sea-fowl, 

 whose various pipes sound harsh discord when heard 

 alone, but when united, form a solemn concert, a tribute 

 of gratitude for that portion of happiness they enjoy. 

 The island of Noss and its holm are composed of sand- 

 stone. Over a chasm between the island and the holm a 

 strong rope is stretched, on which a basket is slung, in 

 which the natives pass over to plunder the nests of the 

 sea-fowl that inhabit the holm, and to carry over a few 

 sheep. There is an incorrect engraving of this place, 

 and the method of passing in the bask^et, published in 

 Pennant's Arctic Zoology, fand from that copied into 

 the Encyclopajdia Britannica), from a rude sketch taken 

 by the late Mr. Lowe, an Orkney parson. 



Anchor in Lerwick Roads : pass over to Brassa, an 

 island composed of sandstone, and of a coarse breccia 

 with a sandstone base, like that already noticed in the 

 neighbourhood of Lerwick. The eastern shores of this 

 island, where they are exposed to the ocean, are lofty 

 precipices like Noss Head, but the southern shores slope 

 gradually to the water's edge. In Brassa and Noss, the 

 strata are not very much inclined. 



Walk along the shore west from Lerwick toward 

 Scot's-hall. The breccia and sandstone continue be- 

 yond the north-west entrance into Brassa Sound. The 

 podules imbedded in the former are larger than in that 

 found near Lerwick. As we go more westerly, the pri-, 

 mary rocks again make their appearance. Leave the 

 shore, and cross some hills, on which we observed mica- 

 ceous schistus, gneiss, and hornblende rock. Descend 

 into the northern end of the vale of Tingwall, where wo 

 again find limestone. Return to Lerwick by the manse 

 of Tingwall, and pick up in several places fragments of 

 striated micaceous schistus, but not so remarkable as that 

 found in Unst. 



Set out in the long-boat to coast the eastern sandstone 

 shores of the Mainland. The coast from Lerwick for 

 some miles seems to be of sandstone or breccia, and is 

 perforated in many places by caves forme4 by the sea, 



and 



