Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/213

 January 11, 1871.

William Salter, Esq., of Maldon, Victoria, Australia, was elected a Fellow of the Society.

The following communications were read : —

1. Oh the Older Metamorphic Rocks and Granite of Banffshire. By T. F. Jamieson, Esq., F.G.S.

Contents.

Introductory.

The three divisions of the strata.

1. The lower division, or Gneiss and Quartz-rock.

2. The middle division, or Slates.

3. The upper division, or Upper Quartz-rock.

The Granite — its origin.

Theory of the derivation of the sedimentary strata and of their present strike.

Introductory.

The information we have regarding the geology of Banffshire is chiefly to be found in Dr. MacCulloch's map of Scotland, a memoir by E. J. Cunningham in the Transactions of the Highland Society, 2nd ser. vol. viii. p. 447, and a paper by Professor Harkness in the Quart. Journ. of the Geol. Soc. for 1862, vol. xviii. p. 331.

Mr. Cunningham's memoir deals with the structure of the whole county, and is accompanied by a map and some sections, while the paper of Professor Harkness describes the section of the rocks exposed along the coast. I have carefully examined the whole of the section described by Professor Harkness, and also the coast eastward as far as Fraserburgh ; but being unable to satisfy myself as to the true succession of all the various beds which are there exposed, I betook myself to the interior of the country; and from an examination of the district lying between the Spey and the Deveron, I was enabled to arrive at clearer views regarding the relation of the various strata to one another, and have constructed a section (fig. 1) extending from near the village of Rothes, on the river Spey, in a south-easterly direction by Mortlach, and the Old Castle of Auchendown, for a distance of about twelve miles, which shows the succession of the beds very distinctly.

The three Divisions of the Strata.

At the bottom we have a great thickness of arenaceous beds, which rise up at the western end of the section, beside the river Spey, and are more or less altered by metamorphic action into quartz-rock, gneiss, and mica-schist (fig. l,a). The base of this series is not exposed, and it seems to extend across the Spey for some distance into Morayshire. In tracing the section eastward, we find these lowermost beds dis- appearing underneath a series of fine-grained argillaceous beds or clay slate (fig. 1, b), varying in colour from green to a very dark, almost