THE SEQUENCE AND CORRELATION OF THE COAL MEASURES OF PEMBROKESHIRE

Abstract

The intensely folded and faulted strata exposed in long cliff-sections in the two structurally detached coalfields of Pembrokeshire (Little Haven–Amroth and Nolton–Newgale) present complex problems of correlation which are considered in detail. Many fossil bands are newly recorded and, where possible, are placed in measured sequences which are correlated by marine bands and are referred to non-marine lamellibranch zones, with occasional use of floral zones. Incomplete Ammanian successions from the Little Haven–Amroth coalfield are generally similar in thickness to corresponding portions of the succession in the western part of the North Crop of the main basin, but evidence exists for marked southward thickening of the basal measures and for moderate attenuation westwards of both the lenisulcata and modiolaris Zones. A tentative succession is proposed for the Morganian of the coastal cliffs, with some sequences assigned to the tenuis Zone and the Rickets Head strata (formerly regarded as the highest Coal Measures in Pembrokeshire) re-assigned to the phillipsii Zone.