84 REPORT — 1876. 



from N.E. to S.W. which are to this day a prominent feature in the physical 

 geof^aphy of the country. 



Fourth. That during that period of disturbance, and as part of the movements 

 which tlien toolt place, the disturbed rocks fell inwards upon materials at a great 

 heat, which rose in a pasty state along the lines of least resistance, and thus 

 came to occupy various positions, sometimes intercalated among the sedimentary 

 beds. 



Fifth. That to this period, and to this method of protrusion we owe some at 

 least of the masses of granitic material which are abundant in the Highlands. Iq 

 particular, that to this period belong the porphyritic granites on the northern shores 

 of Loch Fvne. 



Sixth. That during the later ages of the Palaeozoic period, volcanic action 

 broke out at various points, accompanied by great displacement and dislocation of 

 strata, and that to this, with the denudation which followed, we owe much of the 

 very peculiar scenery of the south-western coasts, especially in the district of Lome 

 in Argyllshire. 



Seventh. That we have no proof that the Central Highlands were ever imder 

 the seas which laid down the deposits of the later Palasozoic age. 



Eighth. That such evidence as we have points ratlier to the conclusion that 

 they were not under those seas, since such fragments as remain of the Old Red 

 and of the Carboniferous rocks appear to have been deposited round the bases and 

 in the marginal hollows of the Silurian hills. 



Ninth. That in like manner we have no evidence that the great mass of the 

 Western or Central Highlands was ever under the seas of the Secondary ages, 

 which on the contrary, appear to have deposited their sediment upon an area outside 

 of, but probably suiTOimding, the area of those Ceuti-al Highlands, and certainly 

 upon their north-eastern and western flanks. 



Tenth. That the whole area of the Inner Hebrides and of the waters dividing 

 them, together with some portion of the mainland, as in Morven, was an area 

 occupied by Secondary rocks. 



Eleventh. That in the Tertiary ages, probably in the Eocene, and certainly in 

 the Miocene, these rocks formed the basis of a great land of unknown extent, very 

 probably extending for a great distance both to the east and west of the present 

 coasts of Scotland, and embracing the north of Ireland. 



Tioelfth. That this country became in the Miocene age, and possibly earlier, the 

 scene of great volcanic outbm-sts, which covered it with vast sheets of lava and 

 broke up its sedimentary rocks with every form of intrusive plutonic matter. 



Thirteenth. That later in the Tertiary periods, and perhaps as late as the 

 Pliocene, this volcanic country was itself broken up by immense subsidences and 

 upheavals, giving both occasion and direction to the agencies of denudation and 

 to enormous removals of material. 



Fourteenth. That this Tertiary country had been thus broken up and nothing 

 but its fragments left when the Glacial epoch began, and that the main outlines of 

 the country, as we now see it, had been already determined when glacial conditions 

 were established. 



Fifteenth. That thus the work of the Glacial period has been simply to degrade 

 and denude preexisting hills and to deepen preexisting valleys. 



Sixteenth. That during the Glacial epoch there was a subsidence of land to 

 the depth of at least 2000 feet below the level of the present sea, and again a 

 reelevation of the land to its present level. 



Seventeenth. That this reelevation has not restored the land to the level it 

 stood at before the subsidence began, but has stopped greatly short of it ; and that 

 the deep arms of the sea or lochs which intersect the country, and some of the 

 deeper freshwater lakes, such as Loch Lomond, are the valleys still submerged 

 whieli at the beginning of the Glacial epoch where high above the sea and furrowed 

 the flanks of loftier mountains. 



Eighteenth. That during the Glacial period the working of denudation and 

 degradation was done, and done only by ice, in the three well-known forms : — 1st, 

 of true glaciers descending mountain-slopes ; 2nd, of icebergs detached from the 

 termination of these glaciers where they reached the sea ; and 3rd, by floe or 



