1824.] Submarine Forest in the Frith of lay. 293 



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 posi- 

 tions 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 nn 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 sub- 

 marine 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 Edinb. Phil. Jour., vol. iii. p. 101. 

 This explanation, 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, eighteen feet in thickness, would be permitted 

 to remain, until washed away by the slow force of percolating 

 fresh water, or that a continuous bed of peat, of nearly an acre 

 in extent, would be spared from destruction, and suffered to 

 settle peacefully, in the Bay of Skaill, so as to be covered at 

 flood-tide with fifteen feet of water. 



If we have no reason to believe that this Tay-bed was trans- 

 ported to its present situation, in what manner has it reached 

 its present level ? Two solutions of this curious question have 

 been offered, as connected with similar occurrences, by eminent 

 individuals, Dr. Borlase, Dr. J. Correa de Serra, and Professor 

 Playfair. 



Dr. Borlase, who, in 1757, observed a submarine forest at 

 Mount's Bay, Cornwall, covered at full tide with twelve feet 

 of water, considered the depression of the bed, which supported 

 the trees, and still contained their roots in situ, as having 

 arisen from subsidence of the ground, produced by earth- 

 quakes, or, to state it in his own words, " that there has been 

 a subsidence of the sea-shore hereabouts, is hinted in my 

 letter to you, p. 92 ; and the different levels and tendencies 

 which we observed in the positions of the trees we found, 

 afford us some material inferences as to the degree and ine- 

 qualities of such subsidences in general ; as the age in which 



