AN UPPER VISÉAN ZAPHRENTOID FAUNA FROM THE YOREDALE BEDS OF NORTH-WEST YORKSHIRE

Abstract

In the Yoredale Beds of North-west Yorkshire the shales immediately above the limestones often contain a fauna of Zaphrentoid phase. One such fauna was recorded by one of us (Hudson, 1925)1 from the three feet of shale overlying the Middle Limestone of Wensleydale. Further collections have been made from the exposure of this shale in Arn Gill, near Askrigg (Hudson, 1933, p. 429 and fig. 48).2 Most of the fossils are small simple corals whose septa meet axially and form a stereocolumn; the majority belong to two morphological groups with considerable variation in each. The following fauna was recorded in 1925 :— Cyathaxonia cornu Mich. Zaphrentis cf. ambigua mut. σ Vaughan Zaphrentis constricta Carruthers Zaphrentis cf. constricta (Densiphylloid variant) Zaphrentis eruca and variants (McCoy), abundant Zaphrentis sp. (cf. Densiphyllum costatum S. Smith, 1910, pl. I, fig. 11) Zaphrentis oystermouthensis Vaughan Similar faunas from comparable horizons were recorded by Garwood (1912) and Turner (1927) from the Westmorland Pennines, and by Carruthers (1922 and 1924) from Northumberland and Dunbar, Scotland. They have also been collected by one of us (R.G.S.H.) from the shales below the Five Yards Limestone of Wensleydale and from the shales, locally known as the Plate-with-Girdles, above and below the Five Yards Limestone of Upper Coverdale and Upper Wharfedale. The Plate-with-Girdles exposed in Slate Pit Beck and in Dowber Gill (Chubb and Hudson, 1925, p. 276) are perhaps the most fossiliferous of all shale exposures in the Yoredale Beds of Yorkshire. One of us (R.G.S.H.) has also re-examined the ...