merely thin outlying portions of those to the westward, lying unconformably on the slightly inclined edges of the Silurian rocks, and resembling in position the thin coal-measures found on each side of the Lickey ridge near the Colmers. There are some circumstances in the structure of this portion of the district which would incline us to the belief that the edge of the Silurian and Coal-measure rocks is here rather an old cliff, or other margin of denudation, than a fault. They are, however, explicable also if we suppose the Silurian rocks to have been slightly undulating, and the fault that traversed them likewise wavy, so that in some places it cut through slight elevations of the Caradoc sandstone, and the lower measures (leaving portions of them, now exposed at the surface, on the upcast side), while in other places it cut through higher beds which now abut against the fault, having the top of the Caradoc sandstone a slight distance beneath them. The discovery of Caradoc sandstone in this district beneath the Wenlock shale, in its characteristic and unaltered condition,—that discovery being due to Mr. Sharpe,—is interesting both in itself, and as confirming, were confirmation necessary. Sir R. I. Murchison's identification of the quartz-rock of the Lickey Hill, as a metamorphosed Caradoc sandstone.
[Note.—The term "Caradoc sandstone"[1] is used here in its old signification,—possibly "Wenlock grits" might be the more appropriate term for these beds.—J. B. J. July 14, 1853.]
3. On the Silurian Rocks of Kirkcudbrightshire. By Robert Harkness. Esq.. F.G.S.. Professor of Geology and Mineralogy. Queen's College. Cork.
[Abstract.]
In the Stewartry of Kirkcudbright[2] the Lower Silurian Rocks, accompanied by igneous rocks, constitute the great mass of the country. From the intrusion of the syenites and porphyries these lower Silurians are much changed both in lithological character and in inclination, being bent into several axial flexures (all apparently intimately connected and possibly contemporaneous[3]) by the syenitic eruptions of Criifel. Cairnsmuir, and Loch Doon, and by the porphyry of Tongueland. The silurian deposits are best seen on the coast. Here precipitous headlands form the margin of the Stewartry, and these afford information concerning these strata, which would otherwise be inaccessible; and here too deposits of a different age are met with. Commencing at the eastern side of the county, we have in
- ↑ See: Caradoc Series. (Wikisource contributor note)
- ↑ In illustration of the observations made in this paper. Mr. Harkness has furnished a Map and Section. The former consists of two sheets (Nos. 54 and 55) of the Ordnance Survey Map, of the 6-inch scale, coloured geologically, and extends from Barlocco Bay to Borness Point. The latter is a coast-section from Netherlaw Point to Bahnae Head, and thence to Cutters Pool, about two miles up the eastern side of Kirkcudbright Bay. The inclined and vertical beds of the cliffs, with some of the intrusive trap-dikes, are represented in detail, and the Section includes a hypothetical representation of the flexures of the strata, as deduced from the various inclinations which are seen exposed.
- ↑ See also Quart. Journ. Geol. Soc, vol. viii, p. 393.
