Freshwater Limestone in Forfarshire, Sgc. 75 



over about 200 English acres ; and to this area the beds of peat and marl, 

 which occupy its former site, are now confined. It was partially drained about 

 70 years ago, and has subsequently, at various intervals, been further reduced 

 in level (see Stat. Account of Scot. vol. ii. p. 212). About 7 years ago it was 

 more completely drained, having for a long time previous been reduced to the 

 state of a peat-moss. 



The ancient banks consist entirely of diluvium, which from the structure of 

 the country must extend also beneath the lake : from the thickness, however, 

 of the more recent deposits, this debris has not yet been reached in cutting 

 the deepest drains through the ancient bed of the Bakie. The retention of 

 water in the hollow of the lake is owing to the clay, which is generally blend- 

 ed with the sand and gravel of the diluvium of Strathmore. This mixture, so 

 impervious to water, is provincially termed "mortar," It is well displayed in 

 a section at Marcus, below the Bridge of Tannadice, on the South Esk ; and 

 was found to constitute the bars of the two great marl-lochs of Logic and Bal- 

 gavies, when the former was completely, and the latter partially, drained. 



Of late years the Bakie has yielded a supply of marl of much importance to 

 the agriculture of the neighbouring district. This deposit is very variable in 

 thickness in different parts of the lake ; and as it has been worked irregularly, 

 at intervals, by different labourers, it is now very difficult to obtain accurate 

 information concerning the manner in which it occurs distributed. The fol- 

 lowing, however, may be considered as a pretty correct section of the beds, be- 

 ginning with the uppermost. 



Thickness. 



1. Peat, containing trees from 1 to 2 feet 



2. Shell-marl, containing, in parts, tufaceous limestone provincially termed -> 



" rock-marl^' J 



3. Quick-sand, without pebbles, cemented together, in some places, by car. 



bonate of lime 



} 



} 0—2 



4. Shell-marl of good quality for agriculture. Almost every trace of shell is-» 



often obliterated J 



5. Fine sand, without pebbles, like No. 3. not sunk through in cutting the- 



great drain, and therefore at least 



This bed of sand, on the borders of the lake, is seen to rest upon the diluvium. 



The following is the section which I saw exposed to the south of the great 

 spring, while the marl was being cast, in October 1824. 



Thickness. 



1. Peat inconsiderable. 



2. Shell-marl 9 feet. 



3. Quick-sand from 2 to 3 



4. Shell.marl 1—2 



5. Quick.sand, like No. 3 unknown. 



l2 



