1849.] GUMMING ON THE TERTIARIES OF THE MORAY FIRTH. 11 



accurate local knowledge, both written and oral, I was privileged to 

 avail myself of. My attention however was chiefly directed to the 

 distribution of the boiilder-clays and the gravels of the tertiary series, 

 and on these I venture at this time to offer a few remarks. Still, as 

 introductory to a description of these more recent deposits, it may be 

 useful to take a hasty view of the general physical contour of the 

 country. 



A very cursory glance at the condition of its surface must convince 

 us that enormous denudation has occurred over the district under 

 consideration. The now isolated masses of old red conglomerate, 

 perched on mountain summits, must clearly at one time have formed 

 continuous strata. We may instance particularly the fine dome- 

 shaped mountain Mealfourvonie, on the western side of Loch Ness, 

 rismg upwards of 3000 feet above the sea. Craigora, rising to the 

 height of 1500 feet above Temple, on the west side of the Eay of 

 Urquhart on Loch Ness, is a round detached mass of old red conglo- 

 merate, which was obviously at one time connected with Mealfour- 

 vonie. Both these mountains rest on a base of red granite, forming 

 nearly two-thirds of their height : and I am not aware of anything 

 which could controvert the position, that the old red series at one 

 time overspread the entire area of Scotland, at least north of the 

 Clyde and Forth. The Grampians themselves were the bed of the 

 ocean in which it was deposited. 



That great disturbances had taken place amongst the schistose and 

 granitoid rocks of North Britain prior to the deposit of the old red 

 conglomerate is very evident, both from the want of conformity 

 between the two series, and the varying thickness of the conglo- 

 merate within very limited areas, showing that there were great 

 irregularities in the then sea-bottom ; but I am not aware of any 

 such general thinning-out of this deposit on the flanks of the great 

 mountain masses, as to lead to the view that any considerable portion 

 of them was eminent above the ocean-level at that time ; and such 

 evidence as we have seems to bear the other way*. 



Of the extent of the disturbance which took place over this northern 

 area, between the periods of the old red sandstone and the lias, there 

 must always be much uncertainty, the subsequent denudations having 

 been to such an extent. That somewhat of the present outline of the 

 country obtained in that interval appears probable. It is very easv 

 to persuade ourselves that a general very gradual elevation of the 

 country had been long taking place prior to the secondary deposits, 

 and that too accompanied with extensive denudations. 



Not only is the inferior gneissose system and the old red sandstone 

 contorted, fractured, and metamorphosed by the intrusion of granite, 

 as we see along the entire coast from Rosemarkie to near Sandwick, 

 and particularly at the Sutors of Cromarty, but also the lias series 



* Mr. George Anderson has observed, that " In the finely serrated mountain- 

 chain of the Maiden-paps in Caithness, the conglomerate rocks rise to a great 

 height ; their highest point, Morvheim, reaching the elevation of 3500 feet above 

 the level of the sea, and overlooking all the primary rocks of the district." (Guide 

 to the Highlands and Islands of Scotland, 1st Ed. p. 190.) 



