132 Rev. Mr Smith on a Submarine Forest 



perhaps be proved, that what happened in one situation might 

 not also happen in another, we cannot conceive that the above 

 explanation extends to such submarine forests as those of Lin- 

 coln and Tiree, where the submarine depositions form a conti- 

 nuous, or nearly continuous stratum, with the interior and un- 

 subsided country. To render the explanation satisfactory, it 

 would be necessary to shew that there was a sinking of the strata 

 supposed to have subsided from their original level ; and while 

 appearances do not permit us to suppose such a sinking, they 

 also forbid us to acknowledge the truth of this theory of subsi- 

 dence. Dr Fleming of Flisk has obviated this difficulty. He 

 found that decayed vegetable formations generally lay upon 

 what he calls Lacustrine silt ; and knowing that lakes suffer a 

 gradual diminution of their depth, owing to earthy, saline, and 

 metallic substances which their waters hold in solution, as well 

 as to particles of detritus supplied by the influx of rivers, and 

 the disintegration of the neighbouring rocks, all of which being 

 deposited, eventually fill up the whole basin of the lake ; he sup- 

 poses that, when a lake situated upon a level with the sea had 

 been thus filled up, and when the earth thus deposited passed 

 into soil fit for the support of "trees, that the seaward barrier may 

 have been broken down, that damage by the tide may have ta- 

 ken place, followed by subsidence, and thus that the soil may 

 be daily covered at flood, which was formerly beyond its reach, 

 and above its level *. 



While I admit the ease with which this accurate observer of 

 nature calls facts to his aid, and explains modes of existence, I 

 would suppose that his theory, encumbered with so many 

 supposed facts, cannot bear with it the force of conviction. It 

 is difficult to establish negative evidence, or to say that all 

 these causes might not have combined in producing the above 

 results. Nothing is supposed which might not possibly have hap- 

 pened ; but it must be acknowledged, that, when a number of 

 fortuitous events is necessary for the explanation of any parti- 

 cular natural occurrence, it is at least a presumptive evidence 

 against the frequency of such occurrences. If the fact to be 

 explained were unique in its nature, we might perhaps, in our 



" Edin. Phil. Journ. vol. xii. p. 120. 



