On the Physical Relations of the Reptiliferous Sandstone near Elgin

Abstract

Abstract R eferring to Sir R. Murchison’s sections of the Elgin district, published in the Quart. Journ. Geol. Soc. No. 59, pp. 424 and 428, which show a conformable sequence of strata from the Old Red Sandstone of Foths to the yellow sandstone and cornstone of Lossiemouth and Burgh Head, the author first stated that the siliceous marly rocks, or so-called “cornstones” of Glassgreen, Linksfield, Spynie, Inveragie, and Lossiemouth are in reality very dissimilar to the cornstones of Foths and Cothall; and he then pointed out the improbability of the so-called cornstone of Glassgreen continuing to dip north-westwardly under the sandstone of the Quarry-wood Ridge, especially as near Linksfield it is, at different spots, seen to dip away from that ridge. Evidence also of a break in the strata at the Bishop Mill quarries was advanced to show that the sandstone beneath this “cornstone” (presumed to be the Reptiliferous sandstone) is probably brought by a fault against the lower or Holoptychian sandstone, which latter towards Spynie the author thinks is surmounted by the Reptiliferous sandstone, and this last conformably by a marly siliceous rock or so-called “cornstone.” Beyond Spynie Loch, northward, the author supposed that another fault had again brought up the sandstone with Stagonolepis and Hyperodapedon at Lossiemouth. Beyond this a cornstone-like rock is again seen to cover the sandstone. The author then referred to the probable Liassic and Triassic character of the shales at Linksfield, and dwelt upon the suggestion that had been offered as to the probability of the layer of boulder-clay beneath the shales having been due to the mass of shales being a portion of a cliff in the glacial period, and having then slipped from a higher level. Regarding these shales as having been removed merely by a slip from their original site, and as conformably over-lying the calcarco-siliceous rock and sandstone beneath, Mr. Symonds expressed his belief that this sandstone, shifted by a fault against the Holoptychian sandstone at Quarry-wood, must be the Reptiliferous sandstone and of Triassic age. Lastly he remarked that the pebble-beds and sandstone, track-marked and rippled, of Burgh Head are far more like the Triassic conglomerates of England than like the Old Red rocks of Cothall and Foths.