REPORT OF MEETINGS FOR 1901 55 



as regards the minor features of the valley, it is certain that, 

 under any circumstances, the harder rocks in the valley of 

 the Forth and its tributaries must have resisted atmospheric 

 wear and tear better than the rocks around, just as they 

 do now, and hence, in the general lowering of the surface 

 by atmospheric waste, these harder parts, wasting less rapidly 

 than the others, were left relatively higher, and stood up 

 as hills. So, when the old volcanic rocks were exposed at 

 the surface, the softer strata around wasted at a much faster 

 rate, and the hard column, consisting of what had once been 

 the molten rock of the volcanic neck, came by slow degrees 

 to stand out in high relief above the rest of the surface. 



After a time, and probably as a consequence of the higher 

 elevation of the land, the Age of Snow set in. This prolonged 

 period of cold led to the formation of a thick mantle of ice, 

 which enveloped all the land, and slowlj' moved seawards 

 from each of the great centres of precipitation, steadily flowing, 

 as it did so, across every obstacle in its way. The summits 

 of the Pentland Hills, for example, were traversed by the 

 seaward moving ice, as was also the summit of North Berwick 

 Law, as anyone may convince themselves was the case if 

 they will examine the glaciated rock-surfaces which yet exist 

 on the north side of its summit. The Bass was, so to speak, 

 a mere pebble in its way ; and it doubtless owes some of 

 the minor details of its form to glacial action. 



The result we are chiefly concerned with here, however, 

 so far as the Age of Snow is concerned, is this: — The weight 

 of a thick mantle of ice, which must have been two or three 

 thousands of feet in thickness at many places in Scotland, 

 is believed by many to be the chief cause which brought 

 about a depression of the land. From being several hundred 

 feet higher above the sea than it is at present, the land was 

 lowered perhaps as much as a hundred and fifty* feet below 

 its present level. So, by degrees, as the ice melted away 

 the North Sea took its place, and sea water occupied the 

 area of the Forth to far above Stirling. It was at this time 

 that the platform upon which Tantallon Castle and the new 

 inn at Canty Bay now stand was carved into its present 



* Some poople think the depregaion ^aH mnGh mori than this. 



