Jan. 11, 1871.] JAMIESON — banffshire mexamorphic eocks. 101 



January 11, 1871. 



William Salter, Esq., of Maldon, Victoria, Australia, was elected 

 a Fellow of the Society. 



The following communications were read : — 



1. On the OiiDEB Metamorphic Eocks and Granite of Banffshire. 

 By T. P. Jamieson, Esq., F.G.S. 



Contents. 

 Introductory. 

 The three dirisions 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. 



Introdttciory. 



The information we have regarding the geology of Banffshire is 

 chiefly to be found in Dr. MacCuUoch'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 ex- 

 posed 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 examina- 

 tion of the district lying between the Spay 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 Eothes, on the river Spey, in a 

 south-easterly direction by Mortlach, and the Old Castle of Auchen- 

 down, for a distance of about twelve miles, which shows the succes- 

 sion 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, h), varying in colour from green to a very dark, almost 



