DR THOMSON ON THE STRATA OF BERWICKSHIRE. *.; 



eggs destroyed, or at least forsaken by the hen, he observed, while a a 

 distance, both birds busily engaged about the brink where the nest was 

 placed, and, when near enough, he clearly perceived that they were add- 

 ing, with all possible dispatch, fresh materials, to raise the fabric beyond 

 the level of the increased contents of the pond, and that the eggs had by 

 some means been removed from the nest by the birds, and were then de- 

 posited upon the grass, about a foot or more from the margin of the 

 water. He watched them for some time, and saw the nest rapidly in- 

 crease in height, but, I regret to add, that he did not remain . long 

 enough (fearing he might create alarm) to witness the interesting act of 

 the replacing of the eggs, which must have been effected shortly after- 

 wards ; for upon his return, in less than an hour, he found the hen 

 quietly sitting upon them in the newly-raised nest. In a few days after- 

 wards, the young were hatched, and, as usual, soon quitted the nest, and 

 took to the water with their parents. The nest was shewn to me /'/< >//// 

 very soon afterwards, and I could then plainly discern the formation of 

 the new with the older part of the fabric. 



Observations on the Strata of Berwickshire and North Durham. By 

 ROBERT D. THOMSON, M. D. 



THE Edinburgh coal-beds which have recently attracted so much 

 attention, in consequence of the discovery in their most ancient elements 

 of several remarkable fossil fish, are interrupted, in their continuity 

 southwards, by the Lammermuir range, and again appear on the banks 

 of the Tweed, along the southern boundary of the Merse. Now, the 

 great problem requiring solution is, What is the age of the Berwickshire 

 strata, which occupy the interval between the Edinburgh and Northum- 

 berland coal-beds ? In a former paper, which I read before this Club 

 soon after its institution, and which was subsequently published, I de- 

 scribed the central part of this county, including, in ray observation-, 

 particularly what 1 termed the New Red Sandstone formation, which 

 comprehends by far the greater portion of the Merse, and was there- 

 fore well deserving of an attentive consideration. My object was simply 

 to describe the rock as it was presented to me during a very careful exa- 

 mination, more especially within the limits to which I then confined 

 myself; and I adopted this name, first, because it had previously been 

 applied to this formation in this particular locality, both by Mr Smith 

 and Mr Greenough, in their respective geological maps of England ; 

 and, second, because I considered the facts which I had accumulated 

 were sufficiently strong in favour of the idea, that this designation liad 

 been correctly applied by these geologists. For, according to the general 

 notions which i>n vailed, relative to the position of the new red sand- 

 stone, it was held by geologists, that the sandstone which lay over mag- 

 n.-i m limestone belonged to this formation, the magnrsian limestone 



