of the Rocks of Shetland. 2^5 
course from the granite of Sandsting, to that part of the epido- 
tic sienite which extends from Sand Voe to Aith Voe ; 
The bluish-grey quartz of Walls and Aithsting; The 
strata maintaining a course from the granite of Sandsting, to 
the bluish-grey quartz of Walls and Aithsting ; 5thly^ The stra- 
ta maintaining a course from the bluish-grey quartz of Walls 
and Aithsting, to the granite of the Islands of Vementry and 
Meikle Rheu ; &hly. The red quartz of the Hill of Walls ; 
'Itlily, The strata maintaining a course from the red quartz of the 
Hill of Walls in a northerly direction, their supposed junction 
with the granite of Meikle Rheu being concealed by the sea ; 
Sthly^ The sandstone, porphyritic claystone, conglomerate and 
amygdaloidal rocks of Sand Ness, and the Island of Papa Stour, 
1^^, The Granite of Sandsting. — I have thus designated the 
rock from the parish in which it occurs. The granite is com- 
posed of a very red felspar and quartz, containing little or no 
mica. Hornblende is occasionally an abundant ingredient, by 
the acquisition of which we have a sienitic rather than a granitic 
rock. This mass, which is what geologists call wedge-shaped, dis- 
plays, in a horizontal section, a truly crystalline appearance. The 
two bounding lines of this wedge-shaped mass, appear to diverge 
from a mere point at the head of Bixetter Voe. The westerly 
line may be traced in a direction of S. 35° W. where it is in 
contact with the quartz last described, to Valey Island. The 
easterly line may be observed in a direction of nearly due south 
to pass through Re wick in Skelda Voe, terminating on the east 
of Skelda Ness. 
^dly, Strata maintaining a course from the Granite of Sand- 
sting to that part of the Epidotic Sienite which extends from 
Sand Voe to Aith Fo^.-r-These strata, in tracing them from the 
south, are first manifested at Rewick Ness, where their actual junc- 
tion with the granite at Skelda Ness is only concealed by the in- 
tervention of the narrow channel of Skelda Voe, From Rewick 
Ness the strata are continued to the Island of Kirkholm and toKii% 
kaness, situated between Selie Voe and Sand Voe, and, lastly, to 
Bixeter Voe, where they are observed to be in junction with the 
epidotic sienite. Thus, the course of the strata is from the gra,^ 
nite of Sandsting to the epidotic sienite. 
