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A detailed isotopic profile is presented for a stratigraphically expanded Cenomanian-Turonian boundary section in Chalk facies exposed at Eastbourne, Sussex and compared with data from Pueblo, Colorado. In both sections macro- and micropalaeontological markers (first appearances and disappearances) are well-constrained, and their relative positions and relationship to the structure of the carbon-isotope curve are identical. This consistent relationship between two independent phenomena, one geochemical, the other biostratigraphical, is taken as evidence for the likely synchroneity of both the biostratigraphical markers and the carbon-isotope excursion in these two areas. This interpretation contrasts with suggestions made recently by other authors whose data have been taken to imply a lack of correlation between the carbon-isotope excursion in Europe and North America.

Geological observations on Jurassic outcrops close to major faults in the Wessex Basin-Mendip area reveal the local presence of ammonite- and brachiopod-bearing sediments penetrating underlying strata. Toarcian and Bajocian neptunian dykes and particularly sills are associated with the Eypemouth Fault and Bajocian sills with the Bride Fault and Mere Fault. In the Mendip area numerous neptunian dykes of Hettangian, Sinemurian, Pliensbachian and Bajocian ages, cross-cutting Carboniferous Limestone, are recorded, typically also associated with major basement faults (e.g. Cranmore and Leighton Faults). These periods of assumed sediment injection are taken as indicating times of displacement along the faults in question.
Variations in facies (Hettangian-Sinemurian, Toarcian, Bajocian, uppermost Oxfordian, Kimmeridgian) spatially linked to faults are documented from some areas, and boreholes reveal considerable fault-controlled thickness changes in Hettangian-Sinemurian, Bajocian and Kimmeridgian sediments. The timing of Jurassic faulting in the Wessex Basin-Mendip area thus polarizes into two intervals: Hettangian-Bajocian and latest Oxfordian onwards, correlating with the early rifting phases of the Central and North Atlantic respectively.

Time series of carbonate and organic-carbon values are reported for 10.5 m of the Belemnite Marls. The light and dark marl beds form decimetre-scale couplets and metre-scale bundles. Light marls are carbon-poor and carbonate-rich whereas dark marls and laminated shales are carbon-rich and carbonate-poor. Sediment composition appears to have been indirectly controlled by climate; the regular couplets may record orbital-precession cycles (20 ka). However, the bundles cannot be linked to changes in eccentricity; rather they apparently record irregular, large-amplitude climatic variations with periods of a few hundred thousand years. It should not be assumed that 100-400 ka cyclicity in climate-related sedimentary sequences can be explained only by orbital forcing.

Pelagic Cretaceous sediments, deposited in a range of palaeotectonic and palaeogeographic settings, from continents to oceans, are commonly black and bituminous. 3 particular time-envelopes define the major occurrences of such facies: late Barremian-Aptian- Albian, the Cenomanian-Turonian boundary and, to a lesser extent, the Coniacian-Santonian. These intervals define the duration of so-called Oceanic Anoxic Events during which global marine waters were relatively depleted in oxygen, and deposition of organic matter, derived from both terrestrial and planktonic sources, was widespread. Cretaceous OAEs correlate closely with transgressions, and such a correlation exists throughout the stratigraphical column. Flooding of land-masses is thought to have transported much terrestrial plant material seawards; the progressive increase in shelf-sea area is thought to have stimulated production of marine plankton. Bacterial consumption of this organic matter favoured the development of poorly oxygenated mid-to late Cretaceous waters in which many of the characteristic facies of the Period, including glauconitic sandstones and phosphatic chalks, were deposited.