76 
Dr Hibbert on the Distrihutlon 
to the lateral planes of the strata of limestone, until a complete 
interception of the mica-slate is induced. The general direc- 
tion of these strata is about N. 12° E. ; the dip is to the west 
at angles from 45° to 70°. 
The strata continuous from the Islands of Great and 
Little Havery^ near Dunrossness^ to the Islands of Yell 
Sound, — These strata are of gneiss, with the exception of a few 
to the east of them, which are of mica-slate, and they are tra- 
versed every where by insulated veins of granite, which often 
contain talc in the place of mica, and occasionally by hornblende 
and sienite. W e trace this very considerable mass of gneiss from 
Great and Little Havery to the large islands of House and 
Burra, to the west of Trondra, to th6 Mainland west of Scallo- 
way, where it forms a long chain of hills, named the Eastern 
Kame, extending to Swinnin Ness and Colafirth Ness, in Yell 
Sound, to the peninsula of Foreholm ; and, lastly, to an is- 
land in Yell Sound, named Weatherholm. 
At Coleness, in the Island of Burra, where the epidotic sien- 
ite, as we trace it from the south, is first manifested, the strata of 
gneiss appear in junction with it. But since the continuity of 
the epidotic sienite with the similar rock of Dunrossness, already 
described, cannot, from the inroads of the sea, be established, 
we can only speak to the great probability there is, that the stra- 
ta of gneiss derive their course from the epidotic sienite. This 
course is uniformly continued in a stratified direction of N. 12° 
E., until the gneiss, a little north of the Head of Olnasfirth Voe, 
begins to be opposed to the hmestone extending from Weesdale 
Voe to Dale’s Voe. The interception of the mica-slate of the 
Long Kame having been accomplished, that of the strata of 
gneiss situated to the east of it follows : accordingly, the course 
of the greatest part of the strata is manifestly terminated in the 
peninsula of Foreholm, which is the most northerly point to 
which v/e can trace the limestone. It is highly probable, that 
in the channel of Yell Sound, the interception of the few re- 
maining strata is completed. 
A subordinate mass of limestone of a very pure quality, occurs 
in the island of Great Havery, whilst another, five miles long, 
and two to three hundred feet broad, may be traced from the 
bridge connecting the islands of House and Burra to Bur wick 
