RAMBLES OP A GEOLOGIST. 333 



species of all the ichthyolites of the system seem to have 

 changed, and, so far as is yet known, the genus Coccosteus 

 died out entirely. 



The Black Isle has been elaborately described in the last 

 Statistical Account of the Parish of Avoch as comprising at 

 least the analogues of three vast geologic systems. The Great 

 Conglomerate, and the thick bed of coarse sandstone of cor- 

 responding character that lies over it, compose all which is 

 not primary rock of that south-eastern ridge of the district 

 which forms the shores of the Moray Frith ; and they are re- 

 presented in the Account as Old Red Sandstone proper. Then, 

 next in order, forming the base of a parallel ridge, come 

 those sandstone and argillaceous bands to which the ichthyo- 

 lite beds belong ; and these, though at the time the work 

 appeared their existence in the locality could be but guessed 

 at, are described as representatives of the Coal Measures. 

 Last of all there occur those superior sandstones of the Lower 

 Old Red formation in which the quarry of the Maolbuie has 

 been opened, and which are largely developed in the central 

 or backbone ridge of the district "And these," says the 

 writer, "we have little hesitation in assigning to the New 

 Red, or variegated Sandstone formation." I remember that 

 some thirteen years ago, in part misled by authority, and in 

 part really afraid to represent beds of such an enormous ag- 

 gregate thickness as all belonging to one inconsiderable for- 

 mation, for such was the character of the Old Red Sandstone 

 at the time, I ventured, though hesitatingly, and with less 

 of detail, on a somewhat similar statement regarding the sand- 

 stone deposits of the parish of Cromarty. But true it is, not- 

 withstanding, that the stratified rocks of the Black Isle are 

 composed generally, not of the analogues of three systems, 

 but of merely a fractional portion of a single system, a fact 

 previously established in other parts of the district, and which 

 my discovery of this day in the Burn of Killein served yet 



