fome Strata in Ireland and Scotland. 77 
It was evening when we failed from hence, and in the morn- 
ing we were fo far to the northward of Raghery, as to have but 
a very imperfed view of its bafalt cliffs, whilft Fairhead and 
Ballycaftle were totally obfcured by the hazinefs of the weather. 
At length, having been four days and nights in the paffage, 
we landed at Loch Loudain, in the eaft fide of Hay. 
The volcanic country, which we exploded together in the 
ifland of Mull, having hitherto remained undefcribed by any 
traveller, I (hall now beg leave to remind you of what we faw 
there, and in our voyage to Staffa ; which may help to confirm 
my opinion refpeding the Ilay Whyn Dykes, which I (hall 
referve for the fubjed of another Letter. 
Sailing from Freeport, in the ifland of Ilay, at ten o’clock 
at night, of Wednesday, July 2, 1788, we paffed Colon fay, 
without being able to diftingui(h the fubftance of its (hores ; 
but entering the found of Iona, we faw that the rude coaft of 
Mull, and the lefs elevated fhore of Iona, was competed of 
red granite. At the landing place in Iona is laminated horn- 
done; and a quarter of a mile north from the ruins of the 
Cathedral is a vein of coarfe red granite, two feet wide, (land- 
ing nearly vertical, and ranging with the hornftone E.N.E* 
and W.S.W. ; on the furface are tumblers of red granite, and 
fome few of lava. About a mile N.W. from the Cathedral, 
and near the (hore, is a vein, two feet wide, containing feld- 
fpath and white mica, ranging E. and W. between granite (ides. 
Many of the rocks are tinged with iron, and there is fome bog 
iron ore in the modes. In the S.W. part of the ifland, is a 
body of white marble, veined with pale green. At the Cove, 
where it is faid St. Columb landed, the cliffs are of red gra- 
nite, and the (hore is covered with great variety of pebbles of 
ferpentine, bafaltes, granite, quartz, and other fubftances. The 
n:w. 
