The Scottish Naturalist. 213 



plained, and which cannot be said to be yet well understood. 

 This arises chiefly from the great difficulty we experience in trying 

 to realize the physical conditions. In our attempts to explain the 

 appearance of the deposits in question, we compare them with 

 what we know of the morainic and fluvio-morainic accumulations of 

 the Alps, and when it is found that our late glacial deposits often 

 exceed these in bulk, some of us are inclined to deny their glacial 

 origin altogether, and to credit their formation to the sea, in 

 whose mysterious depths it is supposed similar accumulations may 

 be in progress. But surely the dissolution of an enormous ice- 

 sheet must have given rise to formations as greatly exceeding the 

 morainic and fluvio-morainic deposits of the present puny alpine 

 glaciers, as our till or boulder-clay supasses in importance all the 

 moraines, whether superficial or sub-glacial, that are at present 

 forming in the mountain-valleys of Switzerland. Having traversed 

 all the glaciated regions of the East of Scotland, I must say I have 

 seen nothing, save our marine-terraces, that I could not parallel 

 with similar phenomena in North Italy and Switzerland. The 

 great hills and ridges of gravel and sand which seem to sweep out 

 from the mouths of the Highland glens, and to dilate, as it were, 

 upon the low grounds of Strathmore, are of precisely the same 

 character as the sand-and-gravel moraines that circle round the 

 lower ends of the Italian lakes. And, just as these last pass 

 laterally into wide sheets of gravel, sand, clay, and loam, so do 

 the morainic accumulations of Strathmore. The wide flats of 

 sand, loam, etc., which sweep along the northern base of the Sid- 

 laws, are simply the fluviatile sediments of the water derived from 

 the melting snows and ice of late glacial times. 



I must not, however, go further into this matter at present, but 

 may conclude my remarks upon it by drawing the attention of our 

 geologists to a very remarkable late glacial accumulation, the origin 

 of which has too often been taken for granted. I refer to the 

 raised beach which occurs at a height of 100 feet upon the coast 

 of Forfarshire. This beach may be followed more or less per- 

 sistently from the mouth of the Tay nearly to Arbroath. But in 

 many places it is much denuded, and forms no marked feature, so 

 that its presence can be detected only in sections. Here and 

 there, however, it makes a conspicuous feature, as at Carnoustie, 

 where it attains half a mile in breadth. The terrace is composed 

 chiefly of well-rounded gravel and shingle, which here and there 



