114 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 8, 



memoir of the Geological Survey. In other instances, although the 

 individual blocks are not large, there are evidently local accumula- 

 tions of fragments from the same bed, perhaps the deposits of single 

 icebergs. The most notable example of the former kind is that of 

 Linksfield, which has been several times brought under the notice 

 of this Society ; while striking instances of the latter kind occur at 

 Inverugie, Lhanbryd, and TJrquhart; these and similar cases have 

 led to reports of the existence of Secondary strata in situ, afterwards 

 proved to be erroneous*. 



With regard to the general relations of the patches of Secondary 

 strata in the east of Scotland to the great masses of Palaeozoic 

 age which constitute the Highlands, the conclusions to which 

 Sir Eoderick Murchison appears to have been led by his first ex- 

 amination of the strata on the east coast of Sutherland were as 

 follows : — That the Jurassic beds were deposited in a basin formed 

 •of the Old Red Sandstone- rocks, and that subsequently a great up- 

 heaval of granite in a solid condition caused the vast amount of 

 ^disturbance and contortion seen in some parts of the strata of the 

 former series f. Later observations appear to have convinced Sir 

 Roderick Murchison that some portions of what he originally re- 

 garded as a granitic rock, were really stratified and metamorphic £; 

 but he has not in his later writings sought to harmonize this fact 

 with the theory of the relations of the rocks which he originally 

 put forward. In the section across Sutherland, published in the 

 'First Sketch of a Geological Map of Scotland' in 1861 §, the Old 

 Red Sandstone and the Jurassic series are represented, probably 

 through inadvertence, as following the Silurian in nearly conform- 

 able sequence. 



Mr. Hay Cunningham, in his examination of the county of Suther- 

 land in 1839, clearly perceived that all the southern part of the 

 crystalline rocks, against which the Jurassic strata of that country 

 lie, are really stratified and metamorphic, and not granitic. In his 

 map he indicates, with tolerable correctness, the range of these 

 metamorphic rocks, though he does not carry them sufficiently far 

 to the southward || ; and he further identifies them with the great 

 series of gneissic rocks which covers so large a part of Suther- 

 land. Rejecting, on these grounds, Murchison's explanation of the 

 peculiar phenomena of the district by the upheaval of granite in a 

 solid condition, Mr. Cunningham himself put forward a theory to 

 account for them, which, however, is likely to find but little accept- 

 ance among geologists at the present day. He argues that the 

 Jurassic strata might have been originally deposited in their present 

 condition of high inclination, and that the "brecciated" appearance 



* See Duff, ' Geology of Moray,' 1842 ; Prestwich, Quart. Journ. Geol. Soc. 

 vol. ii. p. 545 ; Hugh Miller, 'Rambles of a Geologist,' &e. 1858 ; &c. &c. 



t Trans. Geol. Soc. 2nd ser. vol. ii. pt. 2. pp. 295, 307, 354, &c., pi. 31. 



+ Ibid. pt. 3. p. 355. 



§ This Map is republished in Geikie's ' Scenery of Scotland,' 1865. 



|| See also the Map published by the Eev. J. M. Joass, to illustrate the dis- 

 tribution of the auriferous deposits in Sutherland, Quart. Journ. Geol. Soc. 

 vol. xsv. (1869), pi. xiii. 



