1865.] .JAMIESOIT LAST CHANGES IN SCOTLAND, - 171 



place while the ice still kept possession of the unsubmerged land*. 

 This, however, is one of the points regarding which more evidence is 

 greatly wanted. If snch was the case, it is probable that where the 

 ice was thin it melted completely away ; but in other parts, where 

 it was in greater force, it protruded into the sea, its outer edge being 

 floated by the water. In some cases it may have been so thick that 

 the depth of water Avas not sufficient to float it off the bottom, and 

 consequently in such places no marine beds would be formed f. 



Fig. 3. — Section at Springfield BrickworTc, in Fife. 



8. Eiver Eden. N. 



1. Sandstone-rock. 2. Coarse stony earth with ice-worn boulders. 



3. Fine laminated clay or Glacial-marine bed ; has yielded skeletons of Seal 

 (Page). 4. Sand and gravel. 



It is a remarkable fact, that although these marine fossiliferous 

 beds may be traced in many places to a height of 200 or 300 feet 

 above the sea, they are nevertheless totally absent, to all appearance, 

 along many of the valleys in the interior of the country at much 

 lower levels. Thus no mariae fossils have been met with along the 

 valley of the Caledonian Canal between Fort William and Inverness, 

 although the summit-level of that valley is only about 90 feet above 

 the sea ; neither have any been found, so far as I can learn, along the 

 whole line of the Highland Railway from Dunkeld to Inverness. In 

 the valley of the Dee we have some patches of this marine clay and 

 sand, of great thickness in the neighbourhood of the town of Aber- 

 deen, close to the mouth of the river ; but they vanish before we get 

 a couple of miles up the valley, nothing being found beyond that 

 except gravel and boulder-earth. And along all the mountainous 

 seabord of the "West Highlands marine fossils are unknown, except 

 in spots close to the shore and only a few feet above the reach of the 

 tide. On the other hand, in the comparatively low outlying districts 

 of Caithness, North-east Aberdeenshire, and Fife these marine clays 



* This was the theory proposed by Dr. C. Martins, in a clever notice of the 

 glacial phenomena of Scotland., See Edin. New Phil. Journ. for April 1851. 



f The streams of water that escape from beneath glaciers are always loaded 

 with fuie muddy sediment, arising from the friction of the earthy matter pro- 

 duced by the pressure of the moving ice. M. Collomb long ago pointed out 

 that the Loess-beds of certain valleys are accounted for by the deposition of this 

 sediment. Put we may suppose that where glaciers terminate in or near the 

 sea the sttiiF will then go to form submarine mudbanks, like our lammated beds 

 of brick-clay ; and such has probably been the origin of many of these deposits. 

 The formation of loess-beds on land, and brick-clays in the sea, during the 

 Glacial period, therefore harmonizes well with the notion of an icc-covcred 

 country. 



