Introduction 43 



In regard to the Geology of Shetland, three 

 tables are given : the first attempting to show 

 the distribution of the chief formations ; the 

 second illustrating by comparison the total 

 extent of each formation ; and the third show- 

 ing the distribution of representative plants. 



TABLE OF ROCK DISTRIBUTION. ; 



Gneiss. Island of Yell, Hascosay, west 

 side of Unst and Fetlar, Whalsey, Belting, 

 Lunnasting, Tingwall. Also occurring in 

 small quantities here and there ; at Skaw, 

 in Unst, it contains large crystals of felspar ; 

 is often associated with primitive limestone, 

 mica slate, quartz rock, etc. 



Granite. Forms most of Northmaven, on 

 the S.W. on which it is joined by claystone, 

 and on the S. and S.E. by serpentine, and 

 a rock composed of felspar, quartz, horn- 

 blende, and sienite. 



Quartz. Forms most of Walls; also 

 occurs at Burrafirth, near Walls. Is found 

 in many other places, and often associated 

 with limestone and hornblende. 



Mica schist. Forms chief part east side 

 of Unst, and associated with chlorite slate 



