Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/429

1869.] JOASS-SUTHERLAND GOLD-FIELD. 319 gneissose strata (fig. 2). In a paper "On the Metamorphic Rocks of the Banffshire coast, the Scarabins, and a portion of

Fig. 1. — Section showing Granite in Mica-schist at Kil-Donnan Lodge.

Fig. 2. — Granitiform rock in decomposed Gneiss, Suisgill.

1. Decomposed gneissose rocks, dipping S.S.W. and E.S.E.

2. Granitoid rock (c).

East Sutherland," read before the Geological Society in May 1862, Prof. Harkness says:—"The correspondence of the strike of the plutonic masses with that of the metamorphic rocks has been noticed in connexion with these several rocks in Banffshire. In Sutherland it is even more apparent, and supports the inference that here plutonic masses do not perform the office of axes. Their mode of occurrence rather tends to the conclusion that the sedimentary rocks were elevated, flexured, and contorted previous to the period when the granites made their appearance in the sedimentary rocks, and that the granites have conformed in their course to the strike of the previously elevated strata. There are here abundant features which would support the conclusion that granite is, in this district, rather the result of an excessive amount of metamorphic action than a plutonic rock as regards its origin." I venture to think that the coarse-grained porphyritic granite of the Ord (a) should perhaps be regarded as truly plutonic and associated with upheaval, from its coincidence in strike with a great line of fault which traverses Scotland from N.E. to S.W. along the great Caledonian valley.

It is true, indeed, that instead of dipping away from this supposed plutonic and upheaving mass the strata to the N.W. dip towards it, becoming almost vertical as they approach the line of contact. This, however, might be accounted for on the supposition that the upheaved and disrupted rocks, already dipping towards the intrusive mass, would, until it hardened and could support them, dip still more decidedly in the same direction as the result of their weight;