The beds above the Carboniferous Limestone in North-West County Clare, Eire

Abstract

Summary The lithological and faunal succession in the beds above the Carboniferous Limestone over an area of about 50 square miles in North-West County Clare is described. This area has the town of Lisdoonvarna at about the central point and includes the Cliffs of Moher on the Atlantic coastline. Some 1300 feet of beds are preserved above the limestone and are to be referred to the upper part of the Homoceras and Lower Reticuloceras stages of the Namurian. Seventy-three fossiliferous bands, belonging to 10 faunal horizons, have been found and vertical sections measured to show their relationships. The succession, in this part of County Clare, is shown to be very condensed in its lower portion. There exists a considerable non-sequence above the Carboniferous Limestone. The Geological Survey map is shown to embody certain errors and a geological sketch-map is given which attempts to rectify these.

The Western Irish Namurian Basin reassessed

“…Many of the standard European goniatite zones of the lower Namurian are encountered in the Clare Shale Formation of the Shannon Estuary and, although poorly exposed, the transition with the underlying Visean carbonates is considered to be conformable (Hodson, 1954b). In contrast, the Clare Shale rests sharply on Visean limestones in northern County Clare and no goniatites older than the Chokierian Stage are known from this area (Hodson, 1954a;Fig. 2).…”

“…2). A 6-cm-thick bed of phosphate separates the Clare Shale from the limestones (here named the St. Brendan's Well Phosphate Bed, after a stream section 2 km east of Lisdoonvarna) and Hodson (1954a) speculated that much of the Arnsbergian and possibly the Pendleian Stage may be recorded in this highly condensed bed. From the Alportian Stage upwards, the goniatite fauna is generally restricted to thin black shales (known as marine bands) intercalated with sandstones and siltstones of the later stages of the basin ®ll.…”

Short length-scale variability of hybrid event beds and its applied significance

“…The studied section is about 34 m thick from the first sandstone bed thicker than 5 cm, which is taken as the base of the Ross Formation, to the first of the main condensed sections, the H.Smithi marine band (Hodson, 1954;Lien et al, 2003). It is dominantly muddy (>90%) but is punctuated by six thick sandy event beds, the lower three of which are shown Figure 9.…”

Sinuous deep-water channels: Genesis, geometry and architecture

“…The basin fill was initially described by Hodson (1954) and some of its more spectacular features (such as sand volcanoes and synsedimentary deformation features) were documented in detail by Gill and Keunen (1958) and Gill (1979). Research specifically on the Ross Formation came later, with a reappraisal and further documentation of the lower and middle parts of the succession in particular Elliott, 2000a, b;Elliott et al, 2000;Lien et al, 2003;Martinsen et al, 2003).…”