378 



APPENDIX. 



Note F. 



In tlie case of the upper carse on the Tay Firth, there 

 is evidence, both from its vestiges and from records, that 

 it had occupied, at least, the entire firth, or sea-basin, 

 above Broughty Ferry, and that about 50 square miles of 

 this carse has been carried out into the German Ocean 

 by the strong sea-tide current, a consequence of the lower- 

 ing of the German Ocean, and of the deepening of the 

 outlet of this sea- basin at Broughty Ferry, apparently by 

 this very rapid sea-tide current. This carse appears to 

 have been a general deposition at the bottom of a lake 

 having only a narrow outlet communicating with the sea, 

 and probably did not rise much higher than the height of 

 the bottom of the outlet at that time. 



An increase of deposition of alluvium, or prevention of 

 decrease, may, in many cases, be accomplished by artifi- 

 cial means. The diminution of the carse of the Tay was 

 in rapid progress about sixty years ago, the sea-bank 

 being undermined by the waves of the basin, the clay 

 tumbling down, becoming diffused in the water, and 

 being carried out to sea, by every ebbing tide, purer 

 wsitev returning from the ocean the next tide-flow. This 

 decrease was stopped by the adoption of stone embanking 

 and dikes. A small extension of the carses of present 

 high-water level, in the upper part of the firtns of Tay 

 and Forth, has lately been effected, by forming brush- 

 wood, stone and mud dikes, to promote the accumulation. 



