The Late Cretaceous Epoch, which lasted from 100 to 65 Ma, was a time of global sea-level rise, which reached a maximum at the beginning of the middle Turonian (Haq et al. 1987, 1988). The fully marine warm conditions on the shelf seas gave rise to abundant blooms of calcarous nannoplankton that largely formed the resultant Chalk we see today. In addition to the coccoliths, the microfauna contains both plank-tonic and benthonic foraminifera, calcispheres, ostra-cods and the debris of macrofaunal elements, such as inoceramids, echinoids and bryozoans. Within the chalk are horizons of marls and flints, the former from periods of higher clastic/carbonate deposition, and the latter from precipitation of siliceous-rich groundwaters, mostly in burrow systems.
Although the Late Cretaceous seas covered the majority of the British Isles, with the exception of the massifs in the positions of present-day NW Scotland, Cumbria, Cornwall, SW Wales and SW Ireland, much of the chalk deposited there has been removed by later erosion. The present-day outcrop is limited to a broad area from eastern Yorkshire through to Lincolnshire, a broad band from Norfolk to Dorset, then eastwards through Hampshire, and two swathes across the North and South Downs flanking The Weald. There are some chalk outliers in Devon and chalk is also preserved beneath the Tertiary basalts of Northern Ireland (Fig. 1). The stratigraphical coverage of the Late Cretaceous in Britain is largely complete from the Cenomanian to the Campanian; however, only part of the Early Maastrichtian Stage is
Figures & Tables
This book charts the stratigraphical distribution of ostracods in the Cambrian to Pleistocene deposits of Britain and outlines their utility for dating and correlating rock sequences, as well as indicating aspects of their palaeoenvironmental and palaeogeographical significance. These small bivalved crustaceans are the most abundant arthropods in the fossil record. Indeed, the stratigraphy of Britain, which embraces many type-sequences, provides a particularly rich and full record of them, from at least the basal Ordovician, and from the British Cambrian there is a biostratigraphy based on their ‘relatives’, the bradoriids and phosphatocopids. Ostracod distributions demonstrate the ecological success story of the group, occupying as they do marine, non-marine and even ‘terrestrial’ habitats. Written by current specialists in the field, this book is an authoritative account and will be welcomed by all micropalaeontologists and applied geologists in the industrial and academic world alike. It is richly illustrated with over 80 plates of electron micrographs and specially drawn maps, diagrams and range-charts.