Page:Quarterly Journal of the Geological Society of London, vol. 29.djvu/179

1873.] JUDD-THE SECONDARY ROCKS OE SCOTLAND. 135 the Mesozoic strata in the north-east of Scotland having been already given by the late Sir Roderick Murchison, and the important question of the relation of these strata to the Primary rocks fully discussed in the foregoing pages, we may now proceed to a detailed account of the characters presented by each of the Secondary formations as developed in this district. These we shall treat of in chronological order. With regard to the sequence, mineralogical characters, and fossils of the subdivisions of the Mesozoic strata we have three kinds of evidence, which are of very different degrees of value. 1st. The connected series of sections, sufficiently clear though often of limited extent, of the beds seen in situ in Sutherland (see Table I.).

2nd. The sections in the more isolated patches, also in situ, at other points around the shores of the Moray Firth.

3rd. The large transported blocks aud numerous scattered fragments of the various Secondary rocks included in the Boulder-clay of this part of Scotland (see Table II.).

§ 1. The Trias.

On the southern side of the Moray Firth, between the headlands of Burghead and Stotfield, a tract of land projects considerably to the northward of the general line of the coast; at a period geologically very recent, part of this district constituted an island in the Firth, and till late historical times it remained almost separated from the mainland of Scotland by the Loch of Spynie. Within this promontory and in the country bounding it on the south there is developed a formation which, on account of the apparent discrepancy between the stratigraphical and palaeontological evidence as to its age, has attracted much attention and occasioned keen debate among geologists. Under these circumstances, it may be advantageous to distinguish carefully between the conclusions (concerning the relation of these beds) which are the result of direct observation, and therefore not open to question, and such as have been arrived at from inferences of a general character and are still the subjects of controversy.

The formation in question consists of two members, the upper calcareous, the lower arenaceous. A. "The Cherty Rock of Stotfield." — Great differences of opinion have existed among geologists as to the correct designation for this rock. Sir Roderick Murchison calls it a "cornstone," but at the same time points out that it presents characters which distinguish it from the rocks usually included under that name*. Professor Harkness discards the use of the term "cornstone" and calls it simply a limestone†; while the Rev. W. S. Symonds strongly insists that "cornstone," as applied to this rock‡, is altogether a misnomer, and Mr. C. Moore compares the rock to one which occurs


 * Quart. Journ. Geol. Soc. vol. xv. (1859) p. 431.

† Ibid. vol. xx. (1864) p. 431 &c.

‡ Edinburgh Phil. Journ. New Ser. vol. xii. (1860) p. 96.