684 J. W. JUDD ON THE SECONDARY ROCKS OP SCOTLAND. 



Y. Description of the Secondary Strata and Associated Forma- 

 tions in the Western Highlands. 



I will now proceed to give an account of the various formations 

 which are found represented in the singular patches of strata that 

 lie between the old gneiss rocks and Torridon Sandstones of the High- 

 lands on the one hand, and the great masses of superimposed Tertiary- 

 lavas on the other. The Carboniferous, Poikilitic, and Cretaceous 

 systems, as here represented, will demand detailed description at my 

 hands, as they have not before been noticed. With respect to the 

 Jurassic strata, however, I shall only treat generally of those acces- 

 sible and tolerably well known sections which have been illustrated 

 by the writings of other geologists ; and wherever it is possible to do so, 

 I shall simply refer to lists of fossils already published in this Journal, 

 reserving to myself, however, more latitude in describing the sections 

 hitherto noticed but imperfectly or not at all, and seeking especially 

 to illustrate the changes which the several formations are found to 

 undergo as they are traced over considerable areas. 



Even when thus limited, however, I find that the present part of 

 this memoir will extend to a somewhat excessive length, and I am 

 compelled to relinquish the intention I once held of describing, either 

 by myself or with the assistance of others, the new forms of life 

 which I have obtained during my studies. Some of these new 

 forms are undoubtedly of very considerable interest ; but it is desi- 

 rable that they should be described in monographs treating especi- 

 ally of the life-groups to which they belong rather than in connexion 

 with a memoir devoted to the discussion of problems like those with 

 which we are at present concerned. 



A. The Carboniferous System. 



Very interesting, indeed, as affording a well-characterized base on 

 which the remarkable series of Mesozoic strata which we are de- 

 scribing reposes, is the mass of Carboniferous rocks which I had the 

 good fortune to discover in Morvern in the year 1877. Like the 

 Secondary rocks which are superimposed upon them, these Carboni- 

 ferous deposits are a mere vestige of a doubtlessly once widely spread 

 formation which, as the consequence of a concurrence of remarkable 

 accidents, has escaped total destruction through denudation. The 

 patch now remaining for our study is excessively small, extending 

 only for a few hundreds of yards along the shore — on the east being 

 suddenly cut off by a great fault with a throw of something like 

 2000 feet, and on the west being overlapped and concealed by the 

 superincumbent Poikilitic strata. 



What is still more unfortunate is, that these remarkably isolated 

 Carboniferous beds are exposed only in a series of tangle -covered 

 reefs in front of the wild ravine of the Innimore of Ardtornish, and 

 these are uncovered by the sea only at low water during spring- 



