Note on the occurrence of Alethopteris lonchitica in the Carboniferous beds of Loch Ryan

Abstract

Along the western shore of Loch Ryan a narrow strip of Carboniferous rocks is represented on the published geological map of that region. It is traceable for five or six miles, and it is only a few hundred yards wide. It rests unconformably on the Silurian rocks, and is overlain in turn unconformably by a coarse dark red breccia, referred to the Permian formation. Few exposures of the Carboniferous rocks are to be seen, the surface being mostly covered with drift. The strata consist of gray, reddish, and mottled sandstones and purplish clays which have yielded a few fossils, consisting, with one exception, of plant remains in a poor state of preservation. The exception referred to appears to be the remains of an encrinital stem. The following list of fossils, determined by Mr R. Etheridge, junior, is given in the explanation descriptive of the geology of the one inch map:— Alethopteris lonchitica —Sternb. Asterophyllites (like dubia —Brong). Poacites (linear like plant). Calamites dubius —Brong. Stigmaria (like ficoides —Brong, with rootlets attached). The last specimen is too indefinite for a decided opinion to be passed on it. From the presence of these organic remains, the strata containing them were provisionally referred to the Calciferous Sandstone series. Recently, however, a contribution of the highest value has been made to our knowledge of the vertical distribution of fossil plants in the British Carboniferous rocks. In his address to the Royal Physical Society, “On the various divisions of British Carboniferous rocks as determined by their fossil