Four mineralogical zones, corresponding to the following ‘maximum’ metapelitic assemblages

zone 1: chloritoid-chlorite-kyanite

zone 2: staurolite-chloritoid-chlorite-kyanite

zone 3: biotite-staurolite-chloritoid-chlorite-kyanite

zone 4: biotite-staurolite-garnet-chlorite-kyanite

have been mapped in the Ultrahelvetic rocks of the Lukmanier area in Switzerland. Petrographic study suggests that, despite the ubiquity of ‘disequilibrium’, the zone boundaries accord with the simple univariant equilibria

chloritoid+kyanite = staurolite+chlorite+quartz+H2O

chloritoid+chlorite+muscovite = staurolite+biotite+quartz+H2O

and chloritoid+muscovite+quartz = staurolite+garnet+biotite+H26

Using structural contours, minimum isogradic dips of 35° north have been obtained.

The Lukmanier parageneses require the Lepontine phase of Alpine metamorphism to have had a geotherma! gradient distinct from both Alpine blueschists and the Bergell contact metamorphites. The high minimum value for isograd and isotherm orientation here points to a convective heat source for the Lepontine event.

Three new species of Marsupiocrinus are described from the basal Wenlock Laurel Limestone of southeastern Indiana. Although the earliest representatives of the genus yet known, they display fully the specialized characters peculiar to it. Two new subgenera of Marsupiocrinus are erected on the basis of arm structure and cup shape.

The tectonic evolution of Nigeria's Benue Trough has recently been the focus of investigations, especially in relation to continental drift and opening of the South Atlantic Ocean during Cretaceous times. Most of the tectonic models presented for the Benue depression have placed undue emphasis on certain plate tectonic concepts which are inconsistent with the salient geologic features of the trough. A possible model, involving the rise and cessation of mantle upwelling beneath a Cretaceous hot spot, and attendant patterns of doming, rifting, sedimentation, magmatism and tectonism, is proposed for the Benue aulacogen.

Changes attributable to weathering have been detected in Quaternary sediments overlying an important aquifer in the Vale of York. Solution of carbonates is quantitatively the most important effect of weathering. The amount of carbonate dissolved can be estimated from whole rock analyses. The length of time of weathering is known and an equivalent surface lowering rate for limestone can be calculated which is consistent with rates obtained by other workers.The volume of water required to give the observed compositional changes is calculated from porewater analyses. The time period is known and hence the rate of infiltration and the average recharge rate of the aquifer can be determined. The calculated rate of recharge is consistent with rates determined using other methods.

Continental Middle Devonian sediments of the Kvamshesten district have recently been interpreted as a thrusted block. However, although basal contacts in the E of the district are mylonitized, contacts in the W can be interpreted as depositional unconformities. Coarse alluvial-fan breccias (Markavatn Formation) in the district's northern margins interdigitate with fluviatile sandstones (Heilefjell Formation) towards the basin's centre. Syndepositional tectonism is demonstrated by the geometry of the coarse marginal deposits.

Structures similar to the monticules of Palaeozoic trepostomatous Bryozoa which occur in the Jurassic cyclostome Reptomultisparsa incrustans are described. They are interpreted as having a function analogous to that inferred for monticules. A smaller proportion of zooecia open on the monticules than between them, and, of these a higher proportion are occluded.These observations lend support to the theory proposed by Banta, McKinney & Zimmer (1974) that monticules functioned as regions of exhalant current chimneys on the zoarial surfaces of Bryozoa.