340 



SIR A. GE1KIE ON THE TERTIARY 



[May 1896, 



Fig. 



6. — Section at Frod- 

 bonyp, Sudero. 



the Faroes has any one definite platform yet been traced out on 

 which such clays are extensively developed. But various minor 

 and perhaps more local deposits in these regions might be examined 

 as possibly available for industrial purposes. One of the most 

 promising localities lies on the western side of Skye, at the mouth of 

 Loch Bracadale, where, on the face of the great cliff of Eudha nan 

 Clach, some conspicuous bands of lilac and red are interspersed 

 among the basalts. These bands were noticed by Macculloch, who 

 described them as varieties of 'iron-clay/ 1 I have not had an 

 opportunity of examining them, except from the sea at a little 

 distance. But they suggest a similarity to some of the variegated 

 clays between the upper and lower basalt series of Antrim. The 

 coal-bearing platform of the Faroes might also be followed along its 

 outcrop, with the object of ascertaining whether any local deposits 

 of similar clays exist there. 



As an illustration of the diversity of deposits sometimes observ- 

 able between the basalts, I give here a section exposed on the eastern 

 side of Sudero in the Faroe Islands — a locality often visited and 

 described in connexion with its coal-seams (fig. 6). At the base 

 lies a sheet of basalt (a) with an 

 irregularly lumpy upper surface. It 

 may be remarked that the group of 

 basalts below this stratified inter- 

 calation is marked by the occurrence 

 of numerous columnar sheets, some 

 of them possibly sills, and also more 

 massive, solid, and durable basalts 

 than the sheets above. The lowest 

 of the intercalated sediments are 

 light-coloured clays, passing down 

 into dark nodular mudstone and dark 

 shale, the whole having a thickness 

 of at least 20 feet (b). These strata 

 are succeeded by (c) pale clays with 

 black plant-remains, about 3 feet 

 thick. Immediately above this band 

 comes the coal or coaly layer (d), 

 here about 6 inches thick, which im- 

 proves in thickness and quality farther 

 inland, where it has been occasionally 

 worked for economic purposes. A 

 deposit of green and brown volcanic 

 mudstone (e), 12 feet in thickness, 

 overlies the coal and passes under a well-bedded granular green tuff 

 and mudstone 3 feet thick (/). The uppermost band is another 

 volcanic mudstone (g) 4 feet in thickness, dark green in colour, and 

 more or less distinctly stratified, with irregular concretions, and also 

 pieces of wood. Above this layer comes another thick overlying 

 group of basalts (h) distinguished by their abundantly amygdaloidal 



7^ 



Description of the Western Islands of Scotland,' vol. i. (1819) p. 376. 



