1887-88.] An Ancient Lake-deposit ill Qjieen's Park. 139 



^vere selected and -weighed in a chemical balance, when it was 

 found that the hundred weighed only three-tenths of a grain ! 

 So friable were they, that even a slight pressure with a camel- 

 hair pencil in cleaning them reduced many of them to powder. 

 The marl itself is, of course, largely composed of these rubbed- 

 down shells, in the shape of carbonate of lime. Samples of the 

 marl, from different parts of the cutting, were sent to two of 

 our members, Mr Wm. Wallace and ]\Ir Fred. G. Pearcey, who 

 kindly subjected them to a careful independent analysis, and 

 found them to contain respectively 89.4 per cent and 92.35 

 per cent of carbonate of lime. When the use of shell-marl in 

 agriculture was more common than it is at present, a rich 

 deposit like this might have been a good "find." In 1810, 

 at a meeting of the Selkirk Farmers' Club, when Mr Walter 

 — afterwards Sir Walter — Scott was in the chair, " the thirty- 

 six members present discussed with energy the question of the 

 day, ' Whether, in low land of light soil, like the haughs near 

 Selkirk, lime or marl would be most profitable during a nine- 

 teen years' lease, supposing them to be equally cheap?' By a 

 majority of four, it was decided in favour of marl." ^ 



While examining under the microscope the finer particles of 

 the marl, a small insect, like a very minute water-beetle, was 

 observed, of which about a dozen specimens were found, but 

 all in a less or more imperfect condition. This insect proved 

 to be one of the Hydrachnid£e or water-mites, belonging to the 

 family of the Oribatidae, but, owing to the fragmentary nature 

 of the remains, the species was difficult to determine. 



We now come back to the two questions put at the outset 

 of this paper — 1st, How large was this lake originally? and 

 2d, When did it spread out its blue waters under the summer 

 sky ? The answers to both questions can, after all, be little 

 more than mere " guesses at truth." As to the extent of the 

 lake, Mr Henderson is inclined to think that at one time it 

 stretched northwards for a considerable distance, covering the 

 area now occupied by Holyrood Palace and grounds. In the 

 diagram accompanying this paper (fig. 1) the probable extent 

 is given as somewhat less. But that it must have had its 

 greatest dimension from north to soutli may be regarded as 

 certain ; while as to its breadth, it would be confined on 



1 ' Hist, of Selkirkshire,' by T. Craig-Brown, vol. i. p. 243. 



