New evidence of the Cretaceous overstep of the Mendip Hills, Somerset, UK

The Mendip Hills, located on the north-western margin of the Wessex Basin, clearly show the onlap of Upper Triassic to Middle Jurassic sediments onto folded Palaeozoic strata. Recent field mapping on the crest of the Beacon Hill pericline at Tadhill, near Frome, augmented by a suite of shallow boreholes, proved up to 6.2 m of glauconitic grey and green silty sand. These glauconitic sands rest unconformably on Silurian volcanic rocks and Devonian sandstone. Lithological and ipalaeontological analyses of these glauconitic sands indicate that they are part of the Lower Cretaceous Upper Greensand Formation. This provides the first evidence for the Albian transgression across the Mendip Hills. The implications for the Cretaceous overstep on the margins of the Wessex Basin, and the analogies with the Upper Greensand succession in Devon are discussed

Symmetry and phase-selected NMR spectra of liquid crystalline samples

It is demonstrated that the NMR spectra of liquid crystalline samples can be simplified by using multiple quantum filtering. In a system of N spin-Image nuclei, the N or (N-1)-multiple quantum filtered spectra (NQF or (N-1)QF) contain lines which originate only from transitions among the eigenstates belonging to the highest symmetry class of the spin permutation group. In addition the NQF spectra are divided further into two sets of lines which differ in phase by 180°. A method for simulating and analysing multiple quantum filtered spectra is described, with examples from molecules with up to eight interacting spins