of the Rocks of Shetland. 2^9 
afPorded me to judge of the direction of the strata, they appear- 
ed to run about N. 12'’ E. The dip was to the west at a varie- 
ty of angles, generally about 45*. 
Bthly^ The Strata maintaming a Course from the Bluislu 
grey Quartz of Walls and Aithstlng^ to the Granite of the 
Islands of Vementry and Meikle Rhew.—^ln reference to the 
course of these strata, I am obliged to anticipate that a 
very considerable mass of granite occupies the north-west por- 
tion of Shetland, which, in tracing it from the south, is 
first observed in that northerly part of the Island of Yemen-, 
try, which is contained between the Northern Voe on the 
west, and a small inlet of the sea on the east, close to the house 
of Mr Dixon. This mass is continued to the adjoining Island 
of Meikle Hheu, and thence to the parish of Northmavine in 
the Mainland. I shall have occasion to describe hereafter this 
mass of granite, which, in its mineralogical character, resembles 
in a great measure that of Sandsting. 
The strata now under consideration derive their course, as we 
trace them in a northerly direction, from that part of the bound- 
ing line of the bluish-grey quartz, which has been described as 
passing into porphyry, and which may be geographically point- 
ed out as Including the north-westerly angle of the Island of 
Papa Little, the Island of Vementry, with the exception of that 
part which is occupied by the granite, the tract of land south of 
Uyea Sound lying between Braganess and Sonsoness, the ex- 
tremity of the Ness of Nunsburgh, the promontory of the Ne- 
ing, and the south bank of Burra Voe, where it joins the head- 
land of Snarraness. 
The strata consist of gneiss, so associated, however, and inti- 
mately combined with hornblende, that I have given to the 
rock the name of tiornblendic Gneiss. In every specimen which 
we examine, the hornblende is either openly manifested, or is in 
such a state of intimate union with the felspar, as to impart to 
this ingredient of the rock a greenish tinge. Innumerable small 
insulated masses of granite also are every where present, tra- 
versing the strata in all directions ; whilst, occasionally, in the 
place of granite, we observe felspar-porphyry, sienite or sienitic 
greenstone. Several masses of limestone also, of inconsiderable 
extent, maintain a course nearly parallel to that of the adjoining 
