302 Proceedings of the Royal Physical Society. 



Kiver-Terracing in M1NIA.TURE. — Conclusion. 



Although there may be much unwisdom shown in applying 

 the results of observations made in one small corner of the 

 world to all other parts of it, yet it is fair to draw a distinction 

 between isolated observations and essential principles. It was 

 here that the strength of the Huttonian theory lay. The 

 action of running water is in all times and places guided by 

 the same principles. 



To those who will humbly study nature, there is much to 

 be learned from the miniature stream-terraces that may be seen 

 on a sandy sea-shore when the tide has ebbed, or on sand- 

 banks at river-sides, and on spreads of deposit sent from the 

 mouths of drains during a thunder-shower. An instance of 

 miniature-terracing, full of interest and suggestiveness, lately 

 came under the observation of the writer. It was a small 

 runnel, proceeding from a spring, some ten yards away, and 

 flowing over a smooth beach of fine sand at the edge of a river- 

 It is scarcely necessary to give full details of the operations 

 of this little stream. It is enough to say that like larger ones 

 it had its curves, its deflection-banks, at the base of one of 

 which it was still scooping with a force that drove away a 

 brush of sand-grains as if they had vitality in them ; and 

 opposite these little cliffs, it had its terraced slopes, left to 

 one side because the stream had pushed to the other, and 

 marked by the finest possible engraving of terrace-lines, not 

 at equal heights where they chanced to stand opposite. These 

 little amphitheatre terraces we watched in the forming. 



In this case the supply of water was from a spring uniform 

 in its outflow, under conditions in which it could not have 

 been swelled by rains, or even diminished by the drinking of 



level. I am uncertain how many of these, besides the 100 and 50 feet beaches, 

 may have affected the Tweed. A raised beach of 15 feet exists at Holy Island. 

 It may again be pointed out that terraces produced after this fashion ought to 

 be in op])osite pairs. And yet from Mr Milne Home's memoir itself, tlie Tweed 

 terraces may be known to have, to a large extent, no such arrangement. To 

 obtain successive flats, moreover, a stream must be supposed invested with 

 powers of planation, which it would bo absurd to suppose to be limited to 

 horizontal excavation. The theor}^ in fact, concedes to streams powers 

 which, with a sufficient slope to maintain flow, could dispense witli ])ulsations 

 of all kinds, except where they are proved. 



