368 J. BARRELL FLUVIATILE ORIGIN OF OLD RED SANDSTONE 



Ireland. The best continuous exposure is that shown on the southeast 

 coast of Scotland from Stonehaven to. the Firth of Tay. A detailed 

 description of these rocks is given by Hickling, and the following is 

 quoted from him, omitting that of the Stonehaven beds, which are now 

 regarded as Downtonian in age. 



"Table of the Lower Old Red of Forfarshire 



Feet 



Bdzell Shales ? 1,000 



Arbroath Sandstone 1,200 



Auchmithie Conglomerate 800 



Red Head Series 1,500 



Cairnconnan Series 2,000 



Carmyllie Series 1,000 



Dunnottar Conglomerate 5,000 



Stonehaven Beds 1,500 



14,000 



"It must be remarked that the subdivisions in the above table are based 

 purely on lithological characters and are only made for convenience of descrip- 

 tion. No breaks in the series exist to my knowledge, and I am far from sup- 

 posing that these subdivisions are likely to be traceable for any great distance ; 

 rapid lateral variation in the character of the rocks is too obvious a feature 

 of the Old Red Sandstone. The names applied to the subdivisions are taken 

 from the localities where the series may be typically seen. The thickness of 

 the subdivisions are estimated from theoretical sections for the most part, and 

 are therefore to be regarded as only approximately accurate. . . . 



"The Dunnottar Group of coarse red and grey sandstones, grits, and con- 

 glomerates which form the bold coast the whole way from Stonehaven to 

 Johnshaven. As I have only been able to examine the base and the top of this 

 series, I shall add no more than that it forms by far the most extensive series 

 of conspicuously coarse deposits in the district. In its conglomerates pebbles 

 commonly range up to a foot or moi*e in length, and yet are astonishingly well 

 rounded. They mostly consist of quartzite. South of Johnshaven several thin 

 lavas are interbedded with the top of this series, with sandstones and coarse 

 conglomerates of porphyrite blocks between. Beyond this the coast-section is 

 interrupted by the mass of Upper Old Red which is faulted in, extending from 

 East Mathers to Milton Ness (described below), and which covers the junc- 

 tion between the conglomerate series and the great mass of lavas which forms 

 its natural top. These lavas occupy the coast southward by Montrose to 

 Lunan Bay, being hidden, however, almost the whole way to Montrose by sand 

 and alluvium. From Lunan Bay their outcrop strikes inland along the summit 

 of the anticline by Friockheim and Letham, near which latter place they finally 

 die out. About Friockheim and Leysmill are numerous quarry sections of the 



"Carmyllie Series, which overlies the lavas. Compact red or grey sandstone 

 is the predominant rock of this series, with subsidiary masses of grey flagstone 

 and blue or red shale, termed 'caulm' by the quarrymen. Together with their 



