Abstract

Dr L. R. M. Cocks congratulated the author on his paper, and asked for more information on the fossils found. Since the Clare Island sediments were being interpreted as shallow-water in origin, might it not be erroneous to correlate them in age with similar sediments in the Kirkpatrick Inlier on a purely lithological basis, since shallow-water sediments would be expected to be markedly diachronous?

The Author answered that after prolonged search the three fossil localities, described in the text, were found. The most prolific one (06650, 28560) yielded several poorly preserved Lingula sp., 2 orthocone nautiloids and a problematical sea-pen like structure. The fossils are preserved in hematite within red siltstones and mudstones and are very hard to find. The basis of correlation of the Clare Island Silurian is the recognition that the massive sandstones of the Knockmore Sandstone Formation represent the maximum marine transgression, which must be coeval with the Middle Wenlock maximum marine transgression in NW Galway. In the Croagh Patrick Syncline the undated massive sandstones of the Knockfadda Group are also likely to mark the maximum marine transgression, however, an upper regressive cycle has not been recognized. The presence of five distinctive tuff bands in the Strake Banded Formation of Clare Island and in the Oughty Formation of the Croagh Patrick Syncline also suggest their broad contemporaneity. In NW Galway, the presence of Ordovician detritus in the northerly derived Upper Llandovery—Lower Wenlock Gowlaun Member suggests that the Silurian of the Croagh Patrick Syncline, Louisburgh and Clare

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