1873.] JUDD — THE SECONDARY ROCKS OF SCOTLAND. 189 



Hugh Miller*; he did not, however, attempt to account for the ex- 

 traordinary phenomenon presented by them. 



Professor Ramsay, who visited this interesting coast in company 

 with Sir Roderick Murchison in 1859, informed me that he had been 

 strongly impressed by the conviction that the phenomena presented 

 by the " brecciated beds " could only be accounted for by calling in 

 the agency of ice-action ; and he therefore regarded them as possibly 

 aifording evidence of the recurrence in early geological times of 

 glacial periods f. It must be confessed, however, that a careful 

 examination of all the facts exhibits some very startling differences 

 between these deposits of Oolitic age, and ordinary Boulder- clays, 

 or, indeed, any glacial deposits of modern date which have yet been 

 described. 



In a subject which, I must confess, appears to present such re- 

 markable difficulties, it seems to me that the interests of science 

 will be better served by laying before this Society the results of a 

 careful study and analysis of all the phenomena of the case, than 

 by the advocacy of any particular theory. I am confirmed in 

 this view when I reflect on the enormous and startling difficulties 

 which the phenomena of an ordinary Boulder-clay presented to the 

 older geologists, and the wild speculations into which they were 

 thereby led, and consider at the same time how these difficulties 

 and the resulting theories have been alike dissipated, by modern re- 

 searches in physical geography and geology. In the hope and con- 

 fident expectation, therefore, that the study of the forces now acting 

 on the earth, and the changes produced by them, will, at some future 

 time, afford a complete solution of the remarkable phenomena of the 

 " brecciated beds," as it has already done of so many similar diffi- 

 culties, I proceed to describe all such details of their nature and 

 mode of occurrence as seem to me to be capable of throwing any 

 light on their mode of origin, and which I have been able to observe 

 during a long and careful study of them. 



§ 1. Order of Succession of the beds. 



The " brecciated beds," which exhibit so many evidences of the 

 action of violent forces in their deposition, alternate with others 

 which quite as strikingly indicate the quietest subsidence of fine 

 sediments from still waters as their condition of accumulation. These 

 latter beds consist of very finely laminated shales, with occasional 

 thin seams of sandstone, sometimes with the surfaces of the beds 

 covered with crushed specimens of Ammonites and other marine 

 shells ; at other times with the laminae completely covered with vege- 

 table remains, among which occur many beautiful impressions of ferns, 

 cycads, and conifers, while occasionally the vegetable matter is suffi- 

 ciently abundant to form thin imperfect coaly or lignite seams. At 

 intervals, in the midst of a great mass of these finely laminated 

 strata, which reach a thickness of many hundreds of feet, we find beds 



* The Fossiliferous Deposits of Scotland (1854) p. 373; Testimony of the 

 Rocks (1857) pp. 497-8. f Phil. Mag. 4th ser. vol. xxix. (1865) p. 290. 



