of the Rocks of Shetland. 239 
those of Hascosea, the small island of Linga, and in those of 
the west of Unst, where they are intercepted by a mass of ser- 
pentine, remaining to be described. 
The Serpentine and Diallage of Fetlar, and the strata connect- 
ed with them. 
In the Island of Fetlar is a central mass of serpentine, which 
forms the Vord Hill. It is characterised by the quantity of 
chromate of iron which is disseminated throughout, in grains 
not larger than those of gunpowder, by the ferruginous appear- . 
ance which it exhibits on decomposition, and by its noxious 
effect on vegetation. This mass presents two outlines, diver- 
ging from a point in a northerly direction, but inclining a little 
to the north-west ; it is six miles long, and from one to two broads 
To the east of the serpentine, in Grutings Voe, are strata of 
mica-slate, clay-slate and chlorite-slate, associated with several 
small insulated masses of serpentine. These strata, in their 
junction with the large mass of serpentine, are opposed to it at 
various angles. To the east of these, along the whole of the 
east coast of Fetlar, are rocks of conglomerated mica-slate and 
chlorite-slate, containing portions of quartz, occasionally angu- 
lar, but for the most part exhibiting an abraded appearance; 
whilst, at the same time, they are often observed to impercepti- 
bly pass into the substance of the containing mass 
To the west of the central mass of serpentine in Fetlar, are 
numerous insulated masses of serpentine and diallage alternated 
with chlorite-slate, glossy alum-slate, and mica-slate. Still more 
westerly is a cuneiform mass of diallage, and a similarly formed, 
though thinner, mass of serpentine. The serpentine at Odsta 
considerably disturbs the compass. Strata of gneiss, intersect- 
ed by small veins of granite, complete the structure of the Is- 
land of Fetlar ; these bound the western coast, and, in a direc- 
tion of N. by E. and an inclination to the west, meet the serpen- 
tine at various and considerable angles. 
At Lamhoga in Fetlar, in consequence of the decomposi- 
tion of a peculiar white bed of gneiss, containing much felspar, 
* These strata, which several years ago excited the attention of Professor Jame- 
son, appear to have materially assisted his views of the nature of conglomerate 
rocks in general. 
