of the Rocks of Shetland, SS7 
diverge from nearly a point in the Island of Papa Little, of 
which the one is continued in a direction of S. 60° W. to the 
western coast, a little north of the village of Dale ; whilst the 
other extends in a straight line S. 32° W. to the head of Bixe- 
ter Voe, when it first comes in contact with the granite of Sand- 
sting, and thence is continued, in the same direction, to Valey 
Island. 
The quartz is distinguished in colour from that of an adjoin- 
ing mass of a similar kind, by being bluish-grey, and it is various- 
ly found with a compact and granular structure. It admits in- 
to its composition much felspar, which is rendered very evident 
in weathered specimens, containing also, in addition to the fel- 
spar, occasional small portions of clayslate, by which it becomes 
the Grauwacke of some authors. Along its north-westerly line 
of boundary from Papa Little to Kilista Voe, the quartz is por- 
phyritic, including, besides crystals of felspar, angular portions 
of the same, which give to the rock on this occasion somewhat 
of a conglomerated character. At Valey Island and Gruting 
Voe, and along the line where the quartz is joined to the gi’a- 
nite of Sandsting, either an alternation of the two rocks, or a 
transition of one rock into another, by an interchange of sub- 
stance, frequently takes place. Occasionally, however, none of 
these appearances are manifested, and the line of junction is per- 
fectly distinct. 
The stratification of the quartz is only an occasional circum- 
stance, which seems remarkably connected with the partial oc- 
currence of mica. Wherever regular strata are thus produced, 
they range with those of no other contiguous rock, the direction 
being nearly from east to west. Considering, therefore, this in- 
dependency of stratification, together with the crystalline form 
of the quartz, as it appears in a horizontal section, I have little 
hesitation in assigning to it the character of a nucleus. That 
it appears to determine the extent and direction of strata in the 
attachments which it affords to them, will be rendered evident 
when I treat of the rocks in connection with it. 
At the North Voe of Clousta, there occurs, resting on the 
quartz, a small roundish conglomerated mass of granite, felspar, 
and quartz, scarcely, perhaps, more than 150 yards in diameter. 
Such a gradual transition of one rock into the other is obser- 
vable at the junction, as to assign to each a coteraporaneous ori- 
