Revision of certain Lower Ordovician Faunas from Ireland

• Published in: Geological Magazine
• Main Author: Reed, F. R. C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1945
• Subjects: Geology; Canada; Greenland; Gardiner; Newfoundland
• Online Access: http://dx.doi.org/10.1017/s0016756800077967; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756800077967

Since the publication of the papers by Messrs. Gardiner and Reynolds on the Tourmakeady and Glensaul districts in the west of Ireland, with palaeontological appendices by the present author, Raymond (1925, p. 167) has compared the faunas with those of Newfoundland and pointed out some striking resemblances. Other Lower Ordovician faunas have since then been described from various foreign regions, and in the light of this increased knowledge the specimens in the collections from Ireland have been re-examined; this has resulted in revised generic identifications, though confirming the reference of the beds to the Lower Ordovician as the author originally maintained (1910, p. 271). The trilobites, several of which are now put in other genera, are mostly allied to or comparable with species of the Canadian and Ozarkian of North America, Newfoundland, and Greenland which Poulsen (1937, p. 72) correlates with the Arenig and Tremadoc, and they also show resemblances to some of those of the Ceratopyge fauna (Brögger, 1896) of Europe and Western North America (Raymond, 1922) as well as with those of Newfoundland. The brachiopods, the determination of which had been found a matter of much difficulty owing to their poor preservation, possess affinities with many of the American Upper Ozarkian and Canadian species recently named by Ulrich and Cooper (1938), especially with those from Canada, rather than with any of the European forms with which they were previously compared or identified. The admixture of Upper Cambrian fossils with those of the Ceratopyge zone, especially in Nevada and the Mount Robson district, was noted by Raymond (1922, p. 20); and similar interrelations of the two faunas are also traceable in the present case. From the general aspect of the faunas from the Irish localities, Ulrich (1930, p. 19) was inclined to put the beds “about the middle or upper Chazyan”; Grabau (1935, p. 101), relying on the lists of brachiopods and trilobites in the present author’s original papers, would refer them to the Middle ...