188 PROCEEDINGS OE THE GEOLOGICAL SOCIETY. [Jan. 8, 



ceivable shape, all cemented together by a concrete, mainly composed 

 of crushed and waterworn Oolitic fossils. 



This phenomenon must not be confounded with one which has 

 been already described as occurring at Colyburn and elsewhere — 

 namely, that of the crushing up and recementing of the hard sand- 

 stones of the Jurassic series. Not to allude to any other of the nu- 

 merous points of difference between the rocks in the two cases, there 

 are two features which enable us at once to discriminate the one 

 from the ether : — 



1. At Colyburn and in the similar cases the included fragments 

 are composed of the same rock as the matrix, and both, where fossi- 

 liferous, contain the same organic remains of Secondary age ; but in 

 the rocks of the Ord the included masses are certainly foreign to the 

 bed, and they contain Palaeozoic fossils, while the investing matrix 

 is of a totally different character, and yields Jurassic fossils. 



2. In the former cases the masses of included rock are always 

 angular ; but in the latter, while they are sometimes perfectly an- 

 gular, at others they present every degree of attrition, and are not 

 unfrequently converted into perfectly well-rounded pebbles. 



No one can observe the remarkable appearances presented by these 

 " brecciated beds " of the Ord, without being struck by the evidences 

 they afford of the action of forces of the most potent character. 



Sir Eoderick Murchison believed that the phenomenon was to be 

 regarded as the result of the eruption in a solid condition of the 

 granite of the Ord, which, as he supposed, produced, at the same 

 time, both the contortion and brecciated condition of the Oolitic beds. 

 But as we have already seen, Sir Roderick did not recognize, although 

 he seems to have strongly suspected, the foreign nature of the in- 

 cluded fragments. 



Mr. Hay Cunningham, who does not appear to have studied the 

 Secondary beds of Sutherland with that attention and success which 

 characterized his survey of the Palaeozoic rocks of the county, 

 put forward a theory which, merely to state, is to condemn. It is 

 that the " brecciated beds " were formed through the breaking up, 

 by the action of waves on the shore, of certain of the Jurassic beds, 

 and that their redeposition and consolidation in the present inclined 

 positions are due to the same agency. 



We have already seen that the contorted and greatly disturbed 

 position of the beds near the Ord is due to their proximity to a 

 great line of fracture, and is part of a series of phenomena presented 

 by the Secondary rocks, whether brecciated or not, wherever they 

 are seen in contact with the Primary. We thus arrive at the con- 

 clusion that the contortion and the " brecciation " of the rocks are 

 two totally distinct phenomena ; and but little consideration of the 

 facts of the case is required to show that, while the latter must have 

 been produced during the deposition of the strata, the former was 

 the result of forces acting subsequently to their formation. 



The first to point out clearly, from the evidence of organic re- 

 mains, that the masses included in the " brecciated-beds " of the 

 Ord are really of foreign extraction and Palaeozoic age was the late 



