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IRemarks on Natural Terraces or Baised Beaches observed in 

 Scotland, particularly in the course of the Biver Tay. By 

 Charles Maclaren, Esq., F.R.S.E. 



In reasoning on the subject of Natural Terraces or Raised 

 Beaches, we start from a few fundamental propositions : — 



1. The transported and water- worn materials found on the 

 top of the highest mountains, assure us that they have all been 

 at one time covered by the sea, and must have been raised 

 above it in one way or another. 



2. If the land rose from the sea with a constant and uniform 

 motion, the action of the water would disintegrate the rocks, 

 cutting away the softer parts and leaving the harder promi- 

 nent; the broken fragments, sand, and clay, so produced, 

 would form an equal and uniform coating of alluvium (soil) on 

 parts similarly situated — ^thick, of course, in all the valleys, 

 and thinner on all the moderately inclined surfaces, while the 

 salient and precipitous rocks would be left bare. The depth 

 of the coating would also be affected by the presence or ab- 

 sence of currents. 



3. If the land rose with an unequal, or let us say an inter- 

 rupted, motion, marks of the longer action of the water would 

 be visible at those parts where the upward motion was arrested 

 for a time. The long presence of the water at such places 

 would be indicated, first, by indentations on the rocks against 

 which the tides beat ; secondly, by the increased deposit of 

 alluvium, consisting of the gravel, sand, and clay produced by 

 the chafing of the water on the rocks, or carried down by 

 streams, collecting just under the level of low water, and 

 forming a projecting shelf or terrace, such as may be seen in 

 many of our Scottish lakes. We have examples of ancient 

 terraces thus formed in the parallel roads of Glenroy, and in 

 the two raised beaches described by M. Bravais on the coast 

 of Lapland. 



4. The terraces would be broadest and best marked at the 

 mouths of rivers and streams, or in cavities and recesses on 

 their banks, because the materials which form them are there 

 most abundant. 



