ON A SUBMARINE FOREST IN THE FRITH OF TAY. 427 



come a marsh, and a stratum of vegetable matter formed on 

 the surface, of sufficient density to support trees, we arrive at 

 the second condition which is requisite. This state of a 

 marsh, formerly a lake, is of common occurrence, more espe- 

 cially where the surrounding grounds are high, and covered 

 with soil, for in this case the rain washes down earthy parti- 

 cles, and, by spreading them on the grassy surface, renders it a 

 more suitable soil for the growth of trees. 



In this second condition, all the strata below the outlet of 

 the marsh are kept constantly wet, or in a semifluid state. 

 The force of ordinary subsidence, aided by occasional earth- 

 quakes, may render the whole tolerably compact ; yet the quan- 

 tity of water necessarily present, will prevent any thing like 

 the degree of condensation of ordinary alluvial land or soil 

 from taking place. 



Suppose a marsh in this condition to have the level of its 

 outlet lowered, or rather, to have its seaward barrier removed 

 (an occurrence which many circumstances induce us to believe 

 to have happened frequently both on the east and west coasts 

 of this country, where submarine forests are not of rare occur- 

 rence), what consequences would follow ? The extremities of the 

 strata now exposed to the sea, would at every ebb-tide be left 

 dry, to a depth equal to the fall of the tide. Much water, for- 

 merly prevented from escaping by the altitude of the outlet, 

 would now ooze out from the moist beds, and the subsiding 

 force would act more powerfully in the absence of the water 

 which filled every pore. All the strata above low water-mark 

 would thus collapse, and the surface of the marsh, instead of 

 remaining at its original height, would sink below the level of 

 the sea. But the escape of the water from the strata would 

 not, in such circumstances, be confined to the beds situate 

 above the low water-line. Even those occupying a position 



considerably 



