On the Igneous and Associated Rocks of the Breidden Hills in East Montgomeryshire and West Shropshire

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Abstract
The rocks described in this paper occur in a district on the borders of Shropshire and Montgomeryshire, on the east side of the Severn, about 12 miles W. of Shrewsbury and 6 miles N.E. of Welshpool. They are mapped by the Geological Survey, but no detailed description, except a few notices in Murchison's works, has yet been published. There are three chief parallel ridges running N.E. and S.W. The two westerly ones, called the Breidden or Rodney's Pillar Hill (1143′) —extending northwards as far as Brimford Wood—and the Criggan, are composed of intrusive basic rock, and of this there are also one or two other little hills,—the Garreg near Trewern and Foel Coppice to the south, Belan Bank rising out of the alluvial plain of the Severn, and two small hills to the north. The easterly ridge, whose chief summits are Moel-y-Golfa (1199′), Middletown Hill, Bulthey Hill, and Bausley Hill, consists of lavas, ashes, and conglomerates of an intermediate type. Associated with these igneous rocks are shales, sandstones, and mudstones, which appear to be an inlier of the Bala rocks of Shelve reappearing under the Silurian synclinal of the Long Mountain to the S.E., which also seem to reappear as a tiny inlier at Buttington, and are apparently continued further to the S.W. in a strip of similar rocks to the E. and S.E. of Welshpool. In this paper I propose to describe the contemporaneous and intrusive igneous rocks of the region, and to give a short account of the

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