660 J. W. JUDD ON THE SECONDARY ROCKS OF SCOTLAND. 



39. The Secondary Eock:s of Scotland. Third Paper. The Strata 

 of the "Western Coast and Islands. By John W. Jttdd, Esq., 

 F.B.S., Sec. G.S., Professor of Geology in the Eoyal School of 

 Mines. (Read January 23, 1878.) 



[Plate XXXI.] 



Contents. 

 I. Introduction. 

 II. History of Previous Opinion on the Subject. 



III. Distribution and Physical Eelations of the Secondary Strata of the 



Western Highlands. 



IV. General Characters and Succession of the Secondary Strata of the Western 



Highlands. 

 V. Description of the Secondary Strata and associated Formations in the 

 Western Highlands. 



A. The Carboniferous System. 



B. The Poikilitic System. 



C. The Jurassic System. 



a. The Infralias. 



b. The Lower Lias. 



c. The Middle Lias. 



d. The Upper Lias. 



e. The Lower Oolite. 



/. The Great Estuarine Series. 

 g. The Oxford Clay. 



D. The Cretaceous System. 



a. The Upper Greensand and associated beds. 



b. The Strata representing the Chalk. 



VI. Conclusion. 



I. Introduction. 



The existence in the Hebrides and adjoining portions of the Western 

 Highlands of more or less isolated patches of limestone, sandstone, 

 and shale, frequently containing fossils, which are interposed between 

 the gneissic and volcanic formations of the district, has been known 

 to geologists for more than a century. During this period many 

 authors, both British and foreign, who have visited the very inte- 

 resting region in question, have described the peculiar characters 

 presented by some of these curious deposits, their singular relations 

 to the volcanic rocks of the same area, and the remarkable changes 

 which they are in some cases seen to have undergone in proximity 

 to the great igneous masses. In the embittered controversies which 

 so long raged between the Huttonians and Wernerians, too, these 

 deposits were frequently referred to by both parties as lending sup- 

 port to one or other of the rival hypotheses. 



That these deposits of fossiliferous rock would have to be classed 

 with the Secondary series, in the extended and rather vague sense 

 in which that term was then employed, came to be very generally 



