﻿I860.] 



MITCHELL OLD RED SANDSTONE. 



145 



better, for some clear fossil-evidonce, before we can arrive at a 

 positive determination. 



Perhaps the most interesting feature of the district described is 

 the immense development of these bedded greenstones, which may 

 serve as a parallel to the similar phenomenon in Wales ; and to this 

 I would beg to draw the further attention of those interested in the 

 study of trap-rocks. 



2. On the Position of the Beds of the Old Red Sandstone developed 

 in the Counties of Forfar and Kincardine, Scotland. By the 

 Bev. Hugh Mitchell, 



[Communicated by the Secretary.] 

 § 1. The time has now come for us safely to pronounce, from 

 palaeontological evidence, upon the place of those fossiliferous flag- 

 stones, with their associated sandstones and conglomerates, which 

 are spread over a large territory in the counties of Forfar and Kin- 

 cardine, and which are referred to in a paper* read by Prof. Hark- 

 ness before the Geological Society on the 18th January of this 

 present year f. 



The superficial area of country referred to in this paper is almost 

 the same as that in the paper of Prof. Harkness, namely a district, 

 comprehending all the lowland parts of the two counties, bounded 

 on the north by the Grampian Mountains, impinging on the west on 

 the County of Perth, and bounded on the south and east by the 

 German Ocean. The objects of the papers are, however, very different. 

 Prof. Harkness illustrated the stratigraphical arrangement of the 

 rocks by numerous sections along the northern boundary-line, where 

 they lean against the crystalline sehists of the Grampians ; our 

 attention is now directed more to the beds as spread out and ex- 

 hibited in the beautiful tract of country to the south-east of the 

 mountains, and which have of late years begun to yield not a few 

 characteristic and important fossils. It is now wished to state the 

 palaeontological data, collected by the writer in the course of several 

 years, which lead to certain conclusions, in his opinion, sufficiently 

 determining the position and the importance of these rocks in the 

 geological scheme J. 



* Entitled " On the Association of the Lower Members of the Old Eed Sand- 

 stone and the Metamorphic Eocks on the Southern Margin of the Grampians," 

 Quart. Journ. Geol. Soc, vol. xvi. p. 312. 



t See also a paper by the author " On the Flagstones of Forfarshire," ' Geo- 

 logist,' 1859, vol. ii. p. 147 ; his " Notice of New Fossils from the Lower Old 

 Eed Sandstone of Scotland," 'Geologist,' 1860, vol. hi. p. 273; and Mr. W. 

 Powrie's paper " On the Old Eed Sandstone and its Fossil Fish in Forfarshire," 

 ibid. p. 336. 



| The reader is referred to the 11th chapter of 'Siluria,' 2nd edit., 1859, for 

 the latest and most complete review of the history of the Old Eed Sandstone, 

 and for the corrections made by Sir E. I. Murchison in the correlation of the 

 several members of this group. The Table at pp. 432 & 433 of ' Siluria ' gives a 

 general view of the classification adopted by Sir Eoderick, — the Upper, Middle, 

 and Lower divisions of the Old Eed Sandstone of Scotland being respectively 

 synchronized with different zones of the Old Eed and Devonian rocks of Eng- 

 land and Europe. — Edit. 



