a. Geol. Also Twedian. [f. med.L. Tueda the river Tweed + -IAN.] An epithet applied by Geo. Tate in 1856 to the lowest beds of the Carboniferous series, as developed in and near the valley of the Tweed.
1856. R. Embleton, in Proc. Berw. Nat. Club, III. No. 7. 219. These beds form the lowest portion of the Carboniferous formation, lying below the Productal and Encrinal Mountain Limestone of Northumberland, and might properly be designated as the Tuedian group…. Specimens of these fossils were exhibited by Mr. Tate.
1859. Tate, ibid., IV. No. 3. 151. In 1856, I applied this name [Tuedian] to a series of beds, lying below the Mountain Limestone, which are largely developed on the Tweed.
1876. Page, Adv. Text-bk. Geol., xiv. 240. The term Calciferous sandstones … is sometimes employed, as well as the more strictly local one of Twedian beds.
1882. G. A. Lebour in Proc. Berw. Nat. Club, IX. No. 3. 527. This great division … has been … split into two members, the Bernician above,… and the Tuedian below, the equivalent of the Calciferous Sandstone Series and part of the Upper Old Red Sandstone of Scotland.
