ON A SUBMARINE FOREST IN THE FRITH OF TAY. 423 



The first method of explaining the phenomenon likely to pre- 

 sent itself, especially where the bed is limited in extent, is by 

 supposing that the substratum, having lost its adhesion to the 

 bed on which it rested, by the percolation of water, and the 

 exposure of the side next the sea, moved down an inclined 

 plane into deep water, carrying along with it the upper layer 

 of vegetable matter, and the trees growing upon its surface. 

 Such occurrences have taken place in several inland bogs, 

 both in Scotland and Ireland, which have moved out of their 

 positions to a lower level. The extent, however, of this bed, and 

 the horizontality of its layers, prevent us from considering its 

 present depressed position as having been produced by any 

 sliding of this kind. Neither hath it arisen from the washing 

 away of the soft matter on which the bed supporting the trees 

 rested, for the clay still remains, and at the line of junction 

 is much incorporated with the peat. 



This washing away of the subsoil, however, has been resorted 

 to by Mr Watt of Skail, to explain the conditions of a submarine 

 forest on the west coast of Orkney. It occurred to him " that 

 " this bed of moss and trees has arrived at its present level 

 " (so as to be covered, during the flood-tide, to the depth of 

 " at least fifteen feet of water), in consequence of the removal 

 " of a bank of earth, at least eighteen feet deep, which has 

 " been washed gradually away, by the water of the Loch of 

 " Skaill oozing along the rocks upon which it rested, and 

 " upon which the mass of leaves now rests, held together 

 " by the fibres of the roots of the trees." See Edin- 

 burgh Philosophical Journal^ vol. iii. p. 101. This explana- 

 tion, however, is liable to very strong objections. It is not 

 probable, that, on the stormy coast of the west side of Orkney, 

 where the rocks themselves yield to the fury of the waves, and 

 where the top of every cliff is a heap of ruins, a mass of earth, 



VOL. IX. p. II. 3 H eighteen 



