Well-established Late Proterozoic tillites are widely distributed in Svalbard, East and North Greenland, the Norwegian and Swedish Caledonides, Scotland, northwestern Ireland, western USSR, the Urals, Newfoundland and the Appalachians. Recent biostratigraphic and geochronometric data have provided the following sequence of glacial events. The earliest evidence of glaciation is represented by tillites in Newfoundland, Scotland and possibly NE Svalbard, and may have taken place in Late Riphean (sensu Vidal) or Sturtian (sensu Harland) time, perhaps c. 800 Ma ago. A glacial period in Vendian time, the Varangian, centred on 650 Ma was a much more severe climatic event, represented in all the above mentioned areas except Newfoundland. Two Varangian glacial epochs are recorded in Svalbard, East Greenland, northern Norway and possibly western USSR, and although most of the deposits are marine, terrestrial conditions prevailed in some areas with associated periglacial phenomena. The earlier epoch was completed before 650 Ma; the later one occurred within the range c. 650–610 Ma.

A tectonic reconstruction of the region places eastern Svalbard adjacent to East Greenland, which has implications for major strike-slip motions in late and post-Caledonian times. A discrete ice-sheet is envisaged, centred on the western USSR (terrestrial tillites) with ice flowing out to the then peripheral area of the northwestern Europe continental margin and to the Urals where shallow platformal glaciomarine sediments accumulated.

This paper describes the late Precambrian rocks in north-west Oscar II Land, western Spitsbergen, with particular emphasis on an upper (Haaken Formation) and lower (Trondheimfjella Formation) diamictite sequence. It is argued that both diamictites are glacigenic, formed by ice-rafting over distal turbidite basins, and correspond to the two Varangian tillite horizons of northern Norway and elsewhere. This leads to a radical reinterpretation of the age of the Oscar II Land succession, much of which now appears to be Vendian. With the exception of the Trondheimfjella Formation, which records an early phase of deepening of the depositional basin, the lower half of the succession (St Jonsfjorden Group) comprises mainly shallow water shelf sediments. The upper half of the succession (Comfortlessbreen Group) was deposited within a basinward prograding turbidite fan system, with the Haaken Formation representing the distal component of the complex. A return to a mixed clastic-carbonate shelf environment is recorded by the overlying Palaeozoic rocks.

The results of a gravity survey of South Harris show that a residual gravity anomaly of + 220 g.u. occurs towards the southeast of the anorthosite-gabbro-tonalite igneous suite, with a minor low of + 150 g.u. over the anorthosite outcrop and a minor high of + 170 g.u. over the main gabbro outcrop. The distribution of the maximum positive anomaly and the minor anomalies is interpreted as due to interbanding of gabbro and anorthosite. The tonalites do not produce a local anomaly and are interpreted as extending to only limited depth. North of the igneous suite the residual gravity anomaly falls to - 10 g.u. over a hidden granite within migmatitic gneisses. It is suggested that the igneous suite was formed when a large body of gabbroic-anorthositic magma was injected into older continental crust, causing melting and the formation of contemporaneous tonalites, with complex fractionation producing gabbro and anorthosite layering. The sequence of events is interpreted as relating to an igneous episode that was a prelude to continental rifting which predated later phases of metamorphic/orogenic activity.

Ammonites and palynology are described at the Portland-Purbeck junction in the Weald. A major disconformity exists between glaucolithus Zone Portland Beds and the overlying basal Purbeck facies, the basal Purbeck Beds of the Weald are correlated with the Middle Purbeck strata of Dorset. The Cinder Bed of Dorset and Wiltshire is described as one of several marine incursions entering Wessex from further south in the Anglo-Paris basin, not from the Spilsby basin. The use of Cinder Bed as a convenient Jurassic-Cretaceous (Portlandian-Ryazanian) boundary is critically reviewed, as is the placing of the base of the Berriasian Stage in the type Purbeck section. The rival biostratigrahic schemes based on ostracods and palynology are discussed and the discrepancies between the two schemes in southern England are examined.

The Strontian Granodiorite, a ‘Newer Granite’ emplaced late in the Caledonian orogenic cycle, has an aureole which is strongly asymmetrical: the metamorphic zones are broader to the east of the intrusion than to the west. The asymmetry is attributed to a gradient in the background, regional temperatures. The muscovite-out isograd, marking completion of dehydration of muscovite + quartz to sillimanite + K feldspar (estimated temperature 645 °C), lies within 2 km of the contact on the west, whereas the cordierite isograd, due to the onset of dehydration of biotite+sillimanite+quartz (estimated temperature 690 °C) is at least 2.5 km from the contact on the east. This temperature interval of 45 °C, which is rather insensitive to small errors in the estimated pressure (preferred value 4.1 kbar), is used in a simple geometrical treatment to estimate the regional gradient in the plane of present exposure: approximately 5 °C/km in a direction 30° S of E. Because the intrusion does not appear to have been tilted, this result is regarded as an estimate of the horizontal component of the temperature gradient on the west flank of a regional thermal dome, inherited from the regional metamorphic climax and decaying on a timescale which is suggested, by radiometric data in the literature, to be ˜ 10 Ma. A tectonic origin for the perturbed regional temperature distribution (uplift of hot rocks in the east relative to colder rocks further west) is suggested by the metamorphic petrology of the region, and supported by literature data on structural movements, notably of the Sgurr Beag Slide.

This work proposes a mechanism for the formation of the characteristic ‘double cone’ cracking and ‘bulb of percussion with bulbar scar’ cracking caused by the artificial fracture of flint. The double cone fracture is observed as a large, small apex angle, cone that is truncated by a smaller cone of increased apex angle. The author considers that the large narrow apex angle truncated cone of the fracture is caused by Hertzian loading of the flint on impact and the upper complete cone is formed as a result of the unloading of the stressed flint. This mechanism has been deduced from work carried out in the fractography of glass by others and from some restricted laboratory experiments.