Kev. J. Brodie on Level Terraces. 



341 



deposit that may there be thrown up must be proportion- 

 ably higher. We further find that, in creeks and estuaries, 

 which gradually become narrower as they run up into the 

 land, the tide, especially in storms, rises higher and higher 

 as the channel becomes more and more confined. The Bay 

 of Fundy, on the coast of America, where the tide rises and 

 falls fully 40 feet, is an illustration of this remark. The 

 Sol way Firth, with its peculiarly rapid tide, may be referred 

 to as another. The ordinary height of the terrace on those 

 parts of the coast which are not exposed to any great 

 violence of tempest, seems to be from 5 to 15 feet above 

 high-water mark, which is the height to which a full tide 

 wave will be driven by a storm. At the head of estuaries, 

 it appears formerly to have been some 5 to 10 feet higher, 

 while a still greater elevation may be expected in those 

 creeks and inlets which are exposed to the billows of the 

 Western Ocean. 



Inferences to be draivn from these Investigations. 

 The inferences which we draw from these investigations 

 into the action of the natural agencies by which level ter- 

 races are produced, may be stated in three propositions : — 

 1. While these terraces were in course of formation, the re- 

 lative height of the land and water must have remained 

 unchanged. So long as the high-water mark continues 

 stationary, whatever addition may year by year be made to 

 the shore, the height to which the mud or shingle is carried 

 will remain the same ; but if, year by year, the land rises, 

 and consequently the high- water mark descends, so, in like 

 manner, will the comparative height to which the mud or 

 shingle is carried be diminished. A continuous upheaval 

 of any portion of the sea-shore must therefore produce, not 

 a level terrace, but a uniformly sloping bank. 2. Similar 

 arguments serve to show that if the land, after remaining 

 stationary for a time, during which the level terrace has 

 been formed, begins continuously to rise, the terrace will 

 not terminate abruptly, but in a gentle, uniform descent. 

 3. If any portion of the earth's surface has been raised 

 above its former level, the manner in which the elevations 



