TRANSACTIONS OF THE SECTIONS. 91 



by the presence of trilobitic Crustacea, and the general absence of ichthyic formsi 

 The Pterygotus beds were well-marked throughout the whole of Forfar, Perth, Stir- 

 ling, Dunbarton, and Lanark ; and he had little doubt that, when more minute 

 research was directed to the subject in England, they would be found to be equally 

 persistent, though marked, it might be, by the presence of additional local forms* 



On the Freshwater Limestone of Dr. Hibbert. S^ D, Page. 



In introducing this subject, the author remarked, that it was now Upwards 

 of twenty yeafs since Dr. Hibbert's elaborate memoir on the Rurdie House lime- 

 stone was read before the Royal Society of Edinburgh. Since that time little 

 had been done to determine the stratigraphical relations and extent of the Burdie 

 House beds ; and, though the workings had yielded many fossils, no further attempt 

 had been made to identify their geological horizon with other portions of the great 

 Scottish coal-field. At the time Dr. Hibbert made his reseatches, the Burdie House 

 limestone was regarded as a peculiar and anomalous deposit ; and though its earliest 

 investigator had a clear conception of its inferior position to the marine or true 

 carboniferous limestone, he yet failed to exhibit the continuity and extent of its 

 geographical range, or to connect it with its chronological equivalents in other locali- 

 ties. The result of this has been, that while the Burdie House limestone is often 

 quoted as an instance of freshwater or brackish beds occurring in the carboniferous 

 system, it is as often misplaced, and its real geological bearings misinterpteted. For 

 example, in two of our most recetit publications, and these by acknowledged masters 

 of the science, the Burdie House strata are by one placed above the millstone-grit, 

 and by the other ate associated with the mountain limestone. Nothing, however, 

 could be more decided than their subjacent position to the true carboniferous lime- 

 stone. It was a member of the subcarboniferous or lower coal- measure group, 

 and had a range of strike as regular and well-marked as the carboniferous limestone 

 itself. Beginning, for instance, at Burdie HoUse and ttacing it to the horth-east, 

 it was found at St. Catherine's, at Duddingstone, near Holyrood, crossing the Frith 

 of Forth, in the Island of Inchkeith, then at Pettycur, and westward by Brosiehall, 

 Bin of Burntisland, Newbigging, Starleyburn, Balram, on the shore near Inchcolm 

 House, in the low grounds of Donibristle, at B,osyth, beyond Queensferry, and then 

 re-crossing the Forth, in the parish of Abercorn, at Binny, Kirkton of Bathgatej 

 East Calder, in the Water of Leith, and eastward by the Pentlands to Burdie House, 

 Its outcrop thus presented a large elliptical area, and everywhere dipped at varying 

 distances beneath the true carboniferous or mountain limestone. In fact, when the 

 outcrop of the mountain limestone was traced in the same manner, starting at Gil- 

 merton and Moredun, and thence across the Forth, to Seafield of Kinghorn, and 

 Chapel of Kirkaldy, then westward by Glenniston, Little Raith, Bucklivie, Duloch, 

 Charleston — thence across the Forth by Winchburgh and Bathgate, and then east- 

 ward by Midcalder, the Pentlands, and Dryden, to Gilmerton — it presented an 

 almost perfect parallelism and continuity. In fact, the two outcrops exhibited two 

 boldly marked zones on a quaquaversal uprise, of which the Corstorphine Hills 

 might be considered the centre. With the one were associated dark-coloured .shales 

 with bands of ironstone, beds of fire-clay, thin seams of coal, and thick-bedded 

 sandstones like those of Craigleith, Burntisland, and St. Andrews ; with the others 

 were associated calcareous and bituminous shales, black band and clay, ironstones, 

 seams of coal, and coarse quartzose grits. Such were the stratigraphical relations 

 and extent of the Burdie House limestone proper; and its equivalents were to be 

 found ranging in the same manner, beneath the mountain limestone, in the east of 

 Fife and Stirling coal-fields, as well as, he believed, in the Lanark and Ayrshire 

 districts. As to the vertical development of these lower coal-measures, it varied in 

 different districts from 600 to 1800 feet, and he had measured an uninterrupted 

 section near St. Andrews of 1400 feet, consisting chiefly of sandstones, shales, and 

 fire-clays. Respecting the fossils of the Burdie House limestone, not a single coral, 

 coralline, or marine shell had yet been detected in it ; and so far as he was aware, 

 nothing had yet been discovered to invalidate the opinion of Dr. Hibbert, that the 

 limestone with its associated beds were of freshwater or estuary origin. In the 

 lowier coal-taeaSure^, however, considered as a group, he (Mr. Page) had detected 



