in the Neighbourhood of Edinburgh. 267 



in a pelagic bed analogous to one of recent times, the other must 

 have been the result of a fresh- water deposit, which, while it was 

 no less hostile to the growth and increase of marine shells or co- 

 rallines, must have flowed through marshy tracts, wherein grew 

 all the plants observable in our coal-fields. Accordingly, in com- 

 paring the limestone of Burdiehouse with such a limestone as we 

 find at Aberlady, which appears to be formed of one almost un- 

 interrupted aggregate of coralline productions, or with the conti- 

 guous encrinitic limestone of Gilmerton, or with a zone of lime- 

 stone filled with numerous varieties of marine remains, which crops 

 out in a fine of nearly SS.W. to NN.E., from Bathgate to Lin- 

 lithgow, what doubt can remain, that while the limestone of 

 Burdiehouse is of fresh- water origin, that of the other sites enu- 

 merated must be of marine origin ? 



But it is not with such unequivocal marine deposits, that I 

 would dwell long for a comparison, as the line of demarcation is 

 but too obvious. I would prefer drawing a line of difference with 

 such a limestone as I have studied in Derbyshire, which is illus- 

 trative of an estuary. 



The lowest visible portion of the great mass of Derbyshire 

 limestone may be seen at Sherbrook, near Buxton. It is very 

 crystalline, unstratified, and it contains no organic remains what- 

 ever. In the beds above it stratification commences, and the 

 limestone encloses numerous encrinites, corallines, producti, &c. 

 In still higher beds, such as we find at Ashford, indications are 

 rather afforded of a marine estuary, than of an uninterrupted or 

 open sea. Although this limestone abounds with acknowledged 

 marine productions, among which corallines are pre-eminent, I 

 discovered that in some sites the plants of coal-fields were mixed 

 with them, although very sparingly. Among various plants which 

 I collected, one of them was the Sphaenopteris artemisisefolia of 

 Adolphe Brongniart ( See PL 46. of his " Histoire des Vege- 

 tans Fossiles") Other species, some of them new, and perhaps 



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