The Stac Fada Member, which forms part of the Stoer Group, contains the only definitive evidence of volcanic activity within the thick Torridonian succession. At the type area in the Bay of Stoer, four volcanic-rich sandy mudstone units are recognised in the Stac Fada. An irregular erosional contact at the base of the main Stac Fada unit truncates two thinner layers of similar volcanic-rich material that were formerly interpreted as intrusions. Directional sedimentary structures associated with the Stac Fada mass flows, and the distribution and thickness of an accretionary or armoured lapilli tuff, support the existence of at least two volcanic sources. Geochemical evidence suggests that the thick Stac Fada unit at the Bay of Stoer and comparable units to the SW were derived from the same volcanic centre. The chemical composititon of volcanic fragments in the main Stac Fada unit indicates that their potassic nature is not a primary feature but is due to alteration and subsequent metasomatism.

The dermal skull roof of Acanthostega gunnari Jarvik is described in detail, giving new information on the anatomy, and new reconstructions of the skull in dorsal, lateral and occipital views, as well as sections through the skull at two points. The types of suture are compared with those of temnospondyls and discosauriscids, comparable animals in terms of habit and skull shape. The skull-bones of Acanthostega are much more closely integrated with each other than those of the two later groups. However, regions of relatively less firmly and more firmly sutured regions are comparable in position. This may be connected with having the lateral lines accommodated in tubes in Acanthostega rather than grooves, or some other property of the dermal bone in the later groups that reduced the need for stronger integration. The post-orbital region of the skull (skull table) is the most strongly integrated region, possibly connected with the need for attachment of occipital musculature. The skull table and dentition are the most labile of cranial features among Devonian tetrapods, whereas the snout, cheek, palate and infradentary regions remain conservative. These are for the most part the lateral-line-bearing regions of the skull. The specimens of Acanthostega found at one site on Stensiö Bjerg may form part of a year-group that had perhaps come together for spawning.

Although only about 20m thick, the Andersö Shale contains one of the most diverse, if not the most diverse, late Middle-early Late Ordovician faunas known in Baltoscandia. It includes more than 20 trilobite species, more than 20 species of other shelly fossils, about 10 graptolite species, and about 20 conodont species. Based on its lithology, its geographical position near the foreland basin margin, and the presence of trilobites of the raphiophorid association and conodonts of the Periodon-Pygodus biofacies, this formation is interpreted to represent an outer shelf-upper slope (ramp) deposit laid down in moderately deep water. The co-occurrence of some widespread and biostratigraphically diagnostic conodonts, graptolites and trilobites makes it possible directly to compare distribution patterns of these fossils, establish ties between graptolite and conodont zones, and correlate the formation with units elsewhere in Europe, North America and China. Stratigraphically and faunally, the Andersö Shale is of particular interest in straddling the Middle-Upper Ordovician Series boundary as this boundary is recognised in the new global classification of the Ordovician System.

A section of the Vitabäck Clays at Eriksdal in southern Sweden was sampled for vertebrate fossils. Large bulk samples were collected from three horizons, including two coquina beds, VC3 and VC11, and a silty clay bed, VC7. Shark teeth are very common and constitute the main portion of the vertebrate material discussed herein. The selachian tooth faunas are almost exclusively represented by hybodonts, although a single tooth from a neoselachian shark, Squatinidae indet., was recorded from one horizon (VC3). Hybodont species identified from the Vitabäck Clay samples include Egertonodus basanus, Hybodus parvidens and Parvodus rugianus. Hybodont remains, other than teeth, include five morphotypes of placoid scales, incomplete cephalic spines and fragmentary fin spines.

Other fossil groups represented in the sieved residues from the bulk samples include bivalves, gastropods and bony fish. Together with the selachians, they indicate fluctuating palaeosalinities in the area. The lower coquina bed, VC3, includes taxa indicating mesohaline conditions while the composition of the fauna in the other coquina bed, VC11, suggests oligohaline settings. In bed VC7, the presence of amphibian remains and the rarity of selachian fossils indicate an even lower salinity. Palynomorphs from the basal part of the section, immediately below bed VC3, indicate an earliest Cretaceous (Berriasian) age.

The nominal species Mosasaurus ivoensis from the latest early Campanian of the Kristianstad Basin in southern Sweden, is redescribed and assigned to the tylosaurine genus Tylosaurus on the basis of its dental and vertebral morphology. A partial skeleton (KUVP 1024) from the late Coniacian to earliest Campanian Smoky Hill Chalk Member of the Niobrara Formation in western Kansas, USA, was previously referred to “M”. ivoensis. Nevertheless, its marginal teeth are markedly different, both in size and morphology, from those of topotypic T. ivoensis.

Examination of type specimens and topotypic material of the nominal tylosaurines Hainosaurus pembinensis from the late early Campanian of Manitoba, Canada, H. gaudryi from the late Santonian or early Campanian of northwestern France, and H. lonzeensis from the Coniacian or Santonian of Belgium, indicates that all three may be Tylosaurus.

The utility of isolated tooth-crowns in mosasaur taxonomy has been hampered by the often poor quality of the published illustrations of these fossils in combination with poor stratigraphic control. All Swedish remains of T. ivoensis, including 172 marginal teeth, 6 pterygoid teeth, several jawbone fragments and 12 vertebrae, were collected from a narrow stratigraphic interval corresponding to the highest biozone in the German eight-fold division of the early Campanian, providing the first good insight into the intraspecific dental variation in a tylosaurine mosasaur.

It has been known for some years that parallel horizontal structures separated in a vertical plane produce patterns of equally spaced parallel lines that can be detected and mapped by dowsing detector rods, indicating that the patterns are produced by interaction between the structures and the dowsing field, whatever that is. Consequently the arrangement is called a dowsing interferometer and the lines are referred to as interference fringes. The patterns are produced equally well by electrical insulators as by electrical conductors, and the inference that the field is not electromagnetic was confirmed by experiments carried out in an electromagnetically shielded laboratory. Measurements of interferometer fringe spacings made irregularly from 1991 to 1996, analysed retrospectively, were found to be dependent on time of year, decreasing relatively suddenly by a factor of about three in November and increasing again in April. An isolated rise and fall in early March was also found. These results were confirmed by more frequent measurements in 1997 and published the following year. This paper reports a co-operative programme of interferometry between Scotland and New Zealand from 1997 to 2001. The annual pattern of the fringe spacing is clearly defined, with rapid changes between 2m and 6m in November and in April, and an isolated event in early March; but remarkably the pattern in the southern hemisphere is inverted with respect to that in the north. There are differences of a few days in the timings of the events in the north and south, and the amplitude of the March event is increasing.

This paper is a continuation of the work described in Transactions of the Royal Society of Edinburgh: Earth Sciences89 (1998) 1–9.