OF THK LEVEL OF THE SEA. 77 



About 2 feet 3 inches of a poor yellowish clay without 

 sand, but mixed with cockle, mussel, and other marine shells, 

 but no vegetable substances. 4>th, A strong blue clay 3^ 

 feet deep, containing sea shells, and roots of vegetables, the 

 growth of which would seem to have been checked by the 

 superincumbent stratum. 5th, Also a strong blue clay 

 with yellowish seams in it about 5 feet deep, and contain- 

 ing a much greater proportion of vegetable substances than 

 the fourth stratum, but under like circumstances. The 

 river rises to the surface of this stratum in stream-tides. 

 6th, Three feet deep of the same kind of strong blue clay, 

 mixed with more than double the quantity of vegetable 

 roots than in the fifth stratum, but which also seems to 

 have been borne down, and their vegetation extinguished 

 by some superior pressure. These three are separated from 

 each other by a small seam of sand and clay, which forms 

 a pretty exact line of division, and through which the ve- 

 getable roots do not seem to have passed. 1th, A real 

 peat moss, near 4 feet deep, quite full of various kinds of 

 vegetables, with roots, trunks, and branches of trees, the 

 surface of which forms the bed of the Tay ; in many places 

 of which the moss can be distinctly traced perfectly entire, 

 clean, and firm, without having received the least injury 

 from the flux and reflux of the tide, and out of which at 

 other places great quantities of peats have been dug at dif- 

 ferent periods, and are so still. It is very remarkable that, 

 in this stratum, many roots of large trees are to be found, 

 principally alders and birch, at about 13 feet from each 

 other, perfectly upright in the same situation in which the 

 tree had originally grown,* with their ramifications extend- 



* The phenomena of these heds, of comparatively modern date, are 

 most instructive, and throw much light on those of the earlier forma- 

 tions. A fossil forest agreeing most perfectly with the one above de- 



