Mr Milrie 07i the Parallel Rbads of Lothaber. 363 



and which sunk at different perioids,^-^^in most cases, disappearing 

 altogether. 



If, then, the existence of lake-beaches be so common in the val- 

 leys of Scotland, there will be the less hesitation in ascribing the 

 Lochaber shelves to the same cause, — established as that cause has 

 been separately by local evideuce. 



That the occurrence of lake-beacheS in the valleys of Scotlahd 

 should be frequent, is only what every geologist must be prepared 

 to expect, who considers the proofs which may be adduced of thd 

 gradual emergence of the land out of the sea. Some of these proofs, 

 in so far as afforded by Scotland, I shall immediately notice ; but 

 assuming that Scotland was, to the depth of 1300 feet or more, 

 submerged beneath the waters of the ocean, — as it rose out, there 

 would be lakes in every inland hollow, each, of course^ having its 

 river to carry off to the sea, the rain falling on its surface and that 

 of the adjoining mountains. The stream thus issuing, would gra- 

 dually wear down the detritus which formed a barrier at one end of 

 the lake ; and the cutting power of the stream would be gradually 

 increased, as the elevation of the land proceeded ; so that in most 

 cases the blockage of lakes would, in the course of time, be exten- 

 sively undermined and worn down, and sudden depressions of lakes 

 would take place, leaving marks of horizontal shelves along the sides 

 of valleys. 



The progress of these important changes is Indicated, in many 

 parts of the country, by the existence of haughs or river-flats^ far 

 above the present channels of the streams, and which evidently had 

 been formed when they flowed at a much higher level. 



Thus, from Perth up to Loch Tay, a number of isolated flats or 

 terraces occur, forming a pretty uniform level, rising gently inlari(!, 

 and at a rate rather faster than the slope of the river. Near Perth, 

 these old haughs are from 90 to 100 feet, and at Dunkeld about 

 110 feet, above the river. This old haugh at Dunkeld may he 

 traced on both sides of the valley, — Dr Fisher's house being on it 

 at the east side, and Clay potts farm-house on it at the west side. 

 It may even be traced a donsidet-ablo distance up both sides of thei 

 Braan, where it slopes a little to the eastward. 



There is a low haugh at Dunkeld^ which is only about 20 feet 

 above the present bed of the river, and is, therefore^ quite distinct 

 from the higher terrace above described. The ground is now culti- 

 vated and enclosed ; so I suppose that the floods never rise to a level 

 with it now. 



On the Tweed, in like maniier, the rfemains of ancient haughs can 

 be traced in many parts of its course. About half a mile above 

 Berwick Bridge, one may be seen on the south side, from 30 to 32 

 feet above the sea. At Gainslaw, it is 44 feet ; opposite to Finchie, 

 it is 65 or 56 feet ; opposite to Paxton, it is 58 feet ; at Norham, 

 it is 93 feet above the sea. 



