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Published online by Cambridge University Press: 17 January 2013
In this paper I shall first refer to the circumstances under which the following observations were made.
I had gone in the autumn of 1856 for a few weeks to Elie on the Fife coast, and was induced, as a means of relaxation and exercise in the open air, to pay some attention to the geology of the neighbourhood, resuming for a brief interval what was once a favourite pursuit. About a mile to the east of the village, I found a stratum well deserving attention—a thin bed of limestone—dipping inland a little beyond the cliff on which stands the ruined Castle of Ardross. The fossil shells which it contained were of unusual form, and beautifully preserved; there were fish remains of two or three species, and a small group of crustaceans still more remarkable. Among the fish I thought I could detect the large scales of an Irish species—the Holoptychius Portlockii—and among the crustaceans there were the valves of Dithyrocaris, a genus particularly characteristic of the Irish beds. At once the question arose whether these fossils might not serve as links connecting this Ardross bed with the Irish series. The point was of the more importance, that our leading geologists had been differing widely as to the true position of our Scottish coal strata in the geological scale. The lamented Professor Edward Forbes had assigned them a place comparatively high, while Sir Roderick Murchison, with surer judgment, had taken the opposite view and put them beneath the Newcastle coal-field.
page 387 note * It consists chiefly of shales and sandstone, with a few beds of limestone, but is marked thus in the section to express the opinion (here advocated) that the mass is the equivalent of the Mountain Limestone of England—lower portion. The dotted line marks the supposed level which (if the strata had been continuous) would have been occupied by the bed L—the base line of the Mountain Limestone.
Note.—In order to bring the section within proper limits, it has been divided into two parts, but they should be viewed as continuous. For part of the distance between Elie and St Monans a double line of section is given to represent the rocks on both sides of the fault. The inward termination of the, line x x, which marks the course of a stratum across the end of the fault, should have pointed more to the west. The remarkable contortions in the cliffs to the east of St Andrews, and those near Newark Castle, should have been more strongly represented than they are in the section.
page 388 note * Owing to the small size of the section, as given in this paper, it has been impossible to represent the separate beds of limestone, or the sub-divisions of the upper group. For the same reason it has been found difficult to give the angle of dip with anything like minute accuracy. Some of the lesser bending of the strata are omitted—only the general results could be given.
page 388 note † This point is marked in the section by the letter x.
page 390 note * It is not intended in this or the following statements to advance any theory as to the formation of these rocks, the term intrusive being merely used to indicate that the previously formed sedimentary strata must have been consolidated and fractured before these traps could have come into their present position. While on the west the two kinds of rock lie for the most part conformably interstratified, it seemed deserving of notice that on the east side of the basin, when they come into contact there are in most cases clear traces of convulsion. A geologist holding extreme Huttonian or extreme Wernerian opinions might easily enough find on these shores not a few facts in support of his favourite views on either side, but there are still considerable difficulties in the way of any theory which shall explain and harmonise all the phenomena.
page 391 note * The term upper is used only relatively. They form the highest portion of the strata to which this paper refers, underlying the coal-fields.
page 394 note * Mr Salter, MSS.
page 395 note * It was through the kindness of Sir R. Murchison that the specimens were submitted to Sir P. Egerton, our highest authority in fossil Ichthyology.
page 396 note * Since presenting this paper to the Society, I have gone over these beds to the east of St Monans in order to ascertain the thickness of the mass of strata measured in a line perpendicular to the plane of the beds. Taking the direct distance from F to L at right angles to the general strike, and taking the average dip from a series of measurements, the result is that this mass of estuarine beds is about 1400 feet in thickness. Such measurements are of course only approximate.
page 401 note * Mr Salter, MSS. Our fossil is imbedded in the stone, which is to a large extent made up of it; but the weathered surface often shows the fossil very beautifully, the white snake-like form charged with carbonate of lime being well relieved by the dark red of the limestone. The bed occurs among the rocks of the shore near Fife Ness, a short way to the north-west of Balcomie Sands.
page 403 note * See his interesting work ‘The Story of a Boulder,’ p. 195.
