284 Mr Maclaren'*s Remarks on Natural Terraces 



there is certainly not less than 80 feet high. A plane passing 

 along the line of terraces, would not be, I think, horizontal, 

 but inclined ; and its inclination would, in a general way, cor- 

 respond with that of the bed of the river. 



In this diagram, the line y t/ represents the bed of the Tay 

 between Dunkeld and Grandtully, rising to the westward at 

 the supposed rate of 10 feet per mile. If the sea deposited 

 the terraces, we would expect to find them nearly horizontal, 

 as rrr ; and of course declining in their apparent height as 

 we follow them westward. Instead of this, they seem to be 

 ranged in the manner, t, 1 1, ttt; and their height above the 

 river, though very variable, appears to be about as great in 

 the upper part of the valley as in the lower. 



The terraces, however, being in detached parts, occasion- 

 ally with long intervals between them, we may suppose that 

 the western portions ttt^ are fragments of a second or higher 

 line of terraces. If so, remnants of them {u u) should be 

 found somewhere eastward above the others. This is one ex- 

 planation of the facts, and may be the true one. I did indeed 

 see what I considered traces of a second terrace above the 

 first, and a third still higher, at some places, but they were 

 faint and equivocal ; and the proximity of the positions t, 1 1^ 

 sometimes for miles, amounting almost to continuity, with an 

 approximation to uniformity in height, is rather adverse to 

 this supposition. 



Again, it may be supposed, that, when the land rose above the 

 sea, the movement of elevation was not equable, but greater 

 in the interior [than towards the coast. We know that the 

 rate of elevation is variable in Sweden, and have reason to 

 believe that it was so in Britain. ''■ The upheaval may have 

 been greater at ^ / / than at t But this does not account for 



See Mr Murchison's Address to the Geological Society for 1843^ p. 45. 



