THE 
EDINBURGH JOURNAL 
OF 
NATURAL AND GEOGRAPHICAL SCIENCE, 

MARCH 1830. 

ORIGINAL COMMUNICATIONS. 
ART. I. Account of the Series of Islands usually denominated 
the Outer Hebrides. By Witu1am Maceriivray, A.M, &c. 
—( Continued from p. 250.) 
Secr. II.—Geological Constitution of the Outer Hebrides. 
Havineé in a preceding Number introduced the Outer Hebrides 
to notice, by offering some general remarks on their geographical 
nature and relations, I proceed to discuss their geological constitu- 
tion. For understanding what I have to remark on this subject, 
it is necessary that the reader should have a map of tolerable accu- 
racy before him. 
We shall begin with the southern extremity of the range, form- 
_ed by the smal island Ber neray of Barra, generally marked Barra 
Head in charts, and from its important position and imposing as- 
pect, well known to marin ers. This island, which is of an oblong 
_ form, and about a mile in length, consists of gneiss, and ees 
the appearance of a tabular mass, having a perpendicular edge se- 
veral hundred feet high to the south, arid dipping into the ‘water 
on the northern side. The range of precipices on the southern side 
form some of the great breeding-places of the migratory sea-birds, 
of which I shall afterwards have cecasion to speak. Berneray is se- 
parated by a very narrow channel from the next island, Mingalay, 
which is much lar ger, higher, and presents a precipitous face to 
the west. Between ‘the Sarees island and Barra, are seen the is- 
lands of Pabbay, Sanderay, and Vatersay. All these islands con- 
sist of gneiss, intersected by veins of granite and trap, and present 
few remarkable geological appearances. The three last are in part 
VOL. I. 3 EB 
