with Observations on the study of Terraces. 11 



ation of numberless terraces along the rivers of the elevated 

 country. If so, — for the sixty feet rise Scotland has experienced, 

 there must be river terraces of cotemporaneous origin even over 

 the higher lands of the country ; every river will tell the tale as 

 well as the beach along the coast. If so, — the terraces described 

 by Chambers as occurring over these upper regions, cannot all be 

 proofs that the sea there left beaches : and it remains for investi- 

 gation to establish by other evidence than the mere existence 

 of such Ci benches" or " shelves" of land, that any are of that 

 origin. Indeed the whole work, as far as the subject bears upon 

 the question of elevation, remains yet to be done, excepting the 

 observations relating to the exterior of the island. If there have 

 been elevations of the land corresponding to the sea-shore terra- 

 ces of 20, 32, 56, 64, 117, 126, 188 feet, there must for the rea- 

 sons stated, be traces of river-terraces high up on the land, corres- 

 ponding to each elevation, making a most complex problem for 

 investigation to unravel. These facts have led to our separating 

 the sea-shore terraces from the others, in the table given on a 



preceding page. 



8. Another consideration comes in, complicating still more the 

 problem. Suppose the coast to be raised independently of the 

 country back, or to a greater height. This is a possible case, 

 and should be a matter of investigation. It is obvious that the 

 river excavations would be confined to the parts towards their 

 mouths, and here the terraces would be found. At certain places, 

 the slope of the river's bed would be diminished instead of in- 

 creased ; and in such parts the water would be set back : — its 

 bed would fill up ; — its flats would be flooded more frequently 

 than before, or perhaps constantly, and they would consequently 

 increase in height by new accumulations. Near the sea, in such 

 a case, the river terraces might slope with the bed of the stream, 

 while in other places they would be absolutely horizontal, and 

 higher up the valley be wanting altogether. 



9. One important conclusion, obvious without farther remark, 

 is that the terraces in the higher portions of a country are not 

 satisfactory evidences of as many distinct elevations — nor of the 

 actual height of any elevations the country may have experi- 

 enced. The terraces toward the sea are more trustworthy. 





There is a certain rule in the examination of rock deposits — well 

 understood and generally applied — which is entirely neglected by 

 Mr. Chambers and many others in the study of terraces. It is 

 this : — that the marine origin of a bed is to be proved by its re- 

 semblance to marine formations and its containing marine relics. 

 Consider for a moment the characters of a line of coast. 



