NOTES EXPLANATORY OF THE PLATES. 355 



evident to any one who has gone over. I consider the one worked at Crichton Dean to correspond 

 with the Gilmerton limestone lying immediately below the North Greens coal. But I do not know 

 whether the limestone that lies below the Crichton Dean limestone, and which was formerly worked 

 near Woodcot and Fala, corresponds with any known seam beneath the Gilmerton limestone. This 

 lower limestone at Fala, and all the other places where it occurs, is a marine limestone, containing 

 Producta, Terebratula, Orthocera, and all the other shells common in marine limestones. Now the 

 next lowest limestone known on the north side of the district, is the Burdiehouse limestone, which 

 is supposed to be of fresh-water origin, and which certainly has many characters extremely different 

 from the other limestones of the district. Notwithstanding these differences, however, it is possible 

 that the Fala limestone and the Burdiehouse limestone may have been deposited at the same period, 

 and may actually form parts of one general deposit, which varies in character at different places on 

 account of local peculiarities. That the Burdiehouse limestone runs for at least half a mile, in a regular 

 stratum of uniform thickness, is certain, — for the old workings, to the south of Straiton village, were 

 pointed out to me. It therefore hardly deserves the character given to it by Dr Hibbert, of being a mere 

 local deposit of calcareous matter. But I do not go so far as to say, that this limestone forms part of a 

 stratum which reaches to the southern limits of the coal-field. I only maintain, that there is as yet no 

 evidence to the contrary, and that there are some circumstances which render this idea probable. The 

 mere fact, that at Burdiehouse there are in this stratum impressions of terrestrial vegetables, and re- 

 mains of fish and shells which, for anything yet known, may have lived in fresh or in salt water, — is no 

 reason why in a part of the sea, much more distant from the land, similar remains should not occur. 



I may add, that Dr Hibbert was mistaken in imagining that he had discovered a marine limestone 

 at Moredun Mill older and lower than the Burdiehouse limestone. This Moredun Mill limestone forms, 

 in fact, part of the Gilmerton bed, which lies a long way above the Burdiehouse limestone. It will bfe 

 seen from the Map, that it fornis there an extraordinary loop, arising from its taking a counter dip. 



Neither is it true that the Burdiehouse limestone is the lowest limestone in the district, or the 

 only one possessing vegetable exuviae and animal exuviae of ambiguous character. There are below it, 

 and at a great distance, — two other strata, in which I have found these remains in the greatest abundance. 

 These two strata are each from 1^ to 3 feet thick, and they are about 50 yards apart from each other. 

 They crop out at Straiton Mill, — about one-half of a mile from the Burdiehouse quarry. These two 

 strata, there is some reason to think, run all the way to Carlops, for 1 have seen two strata there, of much 

 the same thickness, containing the same fossils, and associated with coal-seams, similar in thickness and 

 character with those occurring at Straiton Mill. 



I have mentioned that the carboniferous strata extend through East-Lothian, as far as the German 

 Ocean. I may add, that though the coal-field apparently terminates on the SW. limits of the district at 

 Coaley Burn, Whitfield, and the Bents, — carboniferous strata re-appear a few miles to the SW,, in 

 Peeblesshire, dipping the opposite way, and forming, as it were, the commencement of another basin. 



2. The Old Red Sandstone Formation is the next in order marked on the Map. But 1 have scarcely 

 any observations of detail to make on it. This formation in many respects resembles the New Red 

 Sandstone ; and judging from its mineralogical appearance, and the entire absence of organic re- 

 mains, it might be easily confounded. In some place;^!, too, especially along the flanks of the Lam- 

 mermuirs, it is very horizontal, — a circumstance countenancing the above opinion ; and indeed, in seve- 

 ral places along that part of the district, there is no reason to suppose that the old red sandstone strata 

 have been elevated since their deposition. On the NW. side of the district, where this formation is in 

 contact with the east parts of the Pentland Hills, the case is different. Tliere they dip at considerable 

 angles. All difficulty and doubt, however, is obviated by the fact, that there red sandstone dips under 



