1873.] 



JUDD — THE SECONDARY ROCKS OF SCOTLAND. 



121 



times the cliff is formed of granite, and the Jurassic beds are only 

 seen in a violently contorted state in the reefs on the shore ; at 

 other points a mass of Oolitic strata highly inclined appears as if 

 attached to the face of a precipice of granite ; while again low pro- 

 montories projecting from the mountains of granite which come down 

 to the shore are seen to be composed of the same greatly disturbed 

 beds. The most noteworthy example of this kind is afforded by the 

 Dunglass, or Green Table, a peninsular mass, composed of highly in- 

 clined Oolitic rocks capped by Boulder-clay, which, projecting from 

 the granite* mountain of the Ord, forms 'the boundary between 

 the counties of Sutherland and Caithness. This singular spot, of 

 which I have given a section (fig. 5), formed the appropriate lo- 



Fig. 5. — Section at Dunglass (Green Table Point). 



a. Granite of the Ord. 



b. Upper Oolite — " Brecciated beds." 



c. Boulder-clay. 



cality of an ancient settlement in the Stone age, as I am informed 

 by my friend Mr. Joass. North of the Green Table the Jurassic 

 strata are found in the county of Caithness, in a patch of highly 

 inclined rock exposed only at low water. 



The remarkable features exhibited by the reefs of these rocks ex- 

 posed on the shore, where by their sudden variations in dip and 

 strike they clearly manifest their crushed and crumpled condition, 

 have been well described by Sir Roderick Murchison, and are illus- 

 trated by the changes of dip which he has recorded on his mapf . 

 The striking appearances which these reefs present are greatly 

 heightened by their being composed of those wonderful " brecciated 

 beds " to which more particular attention will be directed in the 

 sequel. 



§ 3. Relations of the Strata South of the typical line of Section. 

 The peculiar Silurian rock of Clyne Kirk is seen again in a ravine 



* That the great mass of this granite is of very ancient date, and that it has 

 even furnished materials to the Old Red Conglomerate, there appears to be no 

 reason to doubt. Sir Roderick Murchison lias pointed out that it could not have 

 been in a molten condition since the Jurassic period ; for the rocks of that age, 

 though greatly disturbed, are never metamorphosed or penetrated by veins. 

 Below the bridge at Lothbeg, a section, unfortunately somewhat obscure, exhibits 

 veins of granite apparently proceeding from the mass of the Ord and traversing 

 Old Red Sandstone strata. Can it be that we have evidence here of the forma- 

 tion of a granite at the same point at widely different periods? 



t Trans. Geol. Soc. 2nd ser. vol. ii. part 2. plate xxxi. 



