46 The Scottish Naturalist. 



bones, that all the great physical changes of land and sea 

 necessary to account for their present position, took place 

 subsequent to the deposition of the glacial or brick clay, and 

 before the Carse or shell clay, containing mammalian bones, 

 above referred to, was laid down. 



To carry the matter still further down toward our own time, it 

 may be stated that this blue shell clay extends across the estuary of 

 the Eden, where it is seen on the opposite side stretching away 

 under Tentsmuir; whether it crosses the whole muir or not, is 

 scarcely determinable, but the same clay, apparently, is seen on 

 the other side not far from Tayport. Of course Tentsmuir, em- 

 bracing the whole accumulation of that great sand plain, has 

 been heaped together since the Carse or shell clay and its super- 

 imposed beds of loam and gravel were formed. This of itself 

 might take a long time. At any rate, after vegetation commenced 

 to grow on its surface, beds of thin peat have formed here and 

 there on it. At one place facing the estuary of the Eden a bed 

 of peat occurs, which Jias been long quite diy, from nine to ten 

 inches in thickness. This peat does not seem to me to have 

 resulted so much from the growth of the common bog moss, as 

 from the decay of other marsh plants, that had long carried on 

 a struggling and stunted existence on the surface. At what 

 rate peat would form on this sterile and sandy waste, it might be 

 hazardous to venture more than a conjecture. Bearing in mind, 

 however, the nature of the ground, and the class of plants it is 

 capable of supporting, we would perhaps not be over-estimat- 

 ing the rate at which it would accumulate, if we suppose one 

 eighth of an inch in'thickness to have formed in a century; should 

 this be a fair approximation to the time required for the purpose; 

 then Tentsmuir must have remained much in its present con- 

 dition for a long time. 



St. Andrews, I March, 1875. 



THE AURIFEROUS QUARTZITES OF SCOTLAND. 

 BY W. LAUDER LINDSAY, M.D., F.R. S.E., F. L. S. 



SINCE the year 1861, I have, over and over again, both 

 abroad and at home, and in various forms, given public 

 expression to my opinion, that certain districts in Scotland not 

 only contain auriferous drift* but auriferous quartzites. The 



* I use the term Drift rather than Alluvium, because (1) it is shorter; 

 and (2) it is more comprehensive ; while (3) there is, even in modern geo- 

 logical works of the first class, great confusion between these terms and the 



