Trace fossils are abundant and diverse in many clastic sequences spanning the Precambrian-Cambrian boundary and may prove to be the most useful palaeontological method for global correlation in this stratigraphic interval. The ichnofaunas of the latest Precambrian (Vendian) rocks include some forms whose range does not extend into the Cambrian (e.g. Bilinichnus, Intrites, Palaeopascichnus, Vendichnus, Vimenites) and others which continue throughout most or all of the Phanerozoic (e.g. Arenicolites, Aulichnites, Cochlichnus, Didymaulichnus, Gordia, Neonereites, Planolites, Skolithos). At least 50 ichnogenera make their first appearance below the lowest trilobites in sections with broad geographic spread. A few of these appear to have a short time range, extending to about the incoming of the trilobites (e.g. Astropolichnus, Didymaulichnus miettensis, Plagiogmus, Taphrhelminthopsis circularis), but the majority continue through most or all of the Phanerozoic.

For correlation of Precambrian-Cambrian boundary sequences it is therefore possible to use both the occurrence of those ichnogenera with a short time range and the incoming of those with an extended range. Three stratigraphical zones can be recognized with respect to the incoming of trace fossils. Zone I is of Upper Vendian age and includes Arenicolites, Bilinichnus, Cochlichnus, Didymaulichnus, Gordia, Harlaniella, Intrites, Nenoxites, Neonereites, Palaeopascichnus, Skolithos, Vendichnus and Vimenites. In Zone II, of Lower Tommotian age, the earliest examples of Bergaueria, Phycodes, Teichichnus and Treptichnus are encountered. Many trace fossils appear in Zone III, which extends from Upper Tommotian to Lower Atdabanian, but the most important are: Astropolichnus, Cruziana, Diplichnites, Diplocraterion, Dimorphichnus, Plagiogmus, Rusophycus and Taphrhelminthopsis circularis.

This vertical zonation of trace fossils allows an attempt at world-wide correlation, from which the most significant conclusions are that the Vendian/Tommotian boundary can probably be placed: (i) near the middle of the McNaughton Formation in the Rocky Mountains, Canada; (ii) at the base of the Deep Spring Formation or in the underlying Reed Dolomite in the White Inyo Mountains, California, U.S.A.; (iii) low in the Chapel Island Formation in the Burin Peninsula, Newfoundland, Canada; (iv) at or close to the base of the Candana Quartzite in North Spain; (v) at or below the base of the Breivik Member in Finnmark, Norway; and (vi) near or below the base of the Zhongyicun Member at Meischucun, China.

The sections in the Burin Peninsula, Newfoundland and Meischucun, China are favoured candidates for the global stratotype for the Precambrian-Cambrian boundary. In the Burin Peninsula, the trace fossils suggest that the Tommotian/Atdabanian boundary may be within or at the base of the Random Formation, thereby implying that the Tommotian may include a thickness of 500 m of sediment comprising at least most of the Chapel Island Formation. At Meishucun, the ichnofaunal evidence implies that the Tommotian/Atdabanian boundary is probably no higher than the top of the Zhongyicun Member. The thickness of the Tommotian is therefore possibly only about 20 m here, implying a very condensed sequence, a conclusion consistent with an abundance of phosphorites. Two stratotype reference points for the Precambrian-Cambrian boundary have been suggested in this section. The lower point (0.8 m above the base of the Xiawaitoushan Member) may be near the Vendian/Tommotian boundary or younger, while the higher point (base of Unit 7 of the Zhongyicun Member) is probably Upper Tommotian or even Lower Atdabanian. The higher point would place the boundary above the world-wide dramatic increase in trace fossil abundance and diversity but probably before the first trilobites. This would almost certainly have advantages for correlation. The inference that the Meishucun section is younger than most Chinese work suggests should not therefore, by itself, prejudice its adoption as global stratotype.

In general, where comparative data are available, the trace fossil correlations agree well with pre-existing proposals based on small shelly fossils. The degree of resolution of the two methods would appear at present to be similar but trace fossils, being found mainly in clastic facies, may benefit from more frequent occurrence.

The Aguero fanglomerate body developed in late Oligocene to early Miocene time at the northern margin of the Ebro Basin where the emergent southern Pyrenean thrust front created a topographic high. Tectonic activity in the thrust belt strongly influenced the sequences and structures within the fan deposits. The fan deposits display an initial coarsening-up sequence. Intraformational unconformities subdivide the proximal sediments into a series of wedges. These result from a continued uplift along the thrust front during the initial stages of fan development. A major intraformational unconformity marks the top of this sequence and the start of a fining-up sequence. Further tectonic activity in the thrust front is indicated by a syn-depositional synclinal fold which decreases in amplitude up sequence. Rejuvenation of fan sedimentation to form a second coarsening-up sequence reflects renewed activity in the thrust front. This second sedimentation event resulted in a plus 200 m thickness of massive conglomerates. The geographical limits of fan sedimentation can be determined because the fan deposits are lithologically distinct from the other Ebro Basin molasse in the area. The area of the drainage basin of the fan can also be estimated by consideration of the clast types present in the fan deposits. The fan and drainage basin areas are estimated to be 6 km2 and 10 km2 respectively.

Late Caledonian granitoids, (c. 400 Ma) in the zone of the Iapetus suture provide a datum against which current models for the relative timing of deformation can be tested. One such granitoid adjacent to the proposed suture ‘line’ in eastern Ireland is now buried by an Upper Palaeozoic cover. It is identified geophysically by a negative Bouguer anomaly with no magnetic signature, and geologically by a hypabyssal dyke swarm and hornfels metamorphism. The timing of intrusion of the granitoid is shown to have occurred during the continuing end-Silurian/early-Devonian deformation. Other members of this widespread suite in Ireland show features consistent with diapiric intrusion during the later stages of the deformation. This evidence brackets the age of regional deformation as continuing during granite emplacement and cooling (c. 400 Ma). The unifying characteristics of the straddling granitoid suite, coupled with a sinistrally transpressive deformation, in this broad suture zone are interpreted in terms of a continental collision which climaxed in late-Silurian/early-Devonian time.

Numerous acritarchs and stromatolites have been discovered and studied from the Proterozoic Datian Formation of the Kunyang Group and the Meidang Formation of the Dongchuan Group in Sichuan–Yunnan area, southwestern China, and more than 80 oxygen isotope data have been obtained from the sediments. Based on size-range and variation of non-filamentous acritarchs, the development of columnar stromatolites and the 18O/16O values of stromatolitic and nonstromatolitic carbonate rocks, the author proposes, for the first time, a palaeoenvironmental framework of the Kangdian area during Datian–Meidang time.

Although the usefulness of Precambrian acritarchs and oxygen isotope values in palaeoenvironmental analysis of a sedimentary basin is just beginning to be understood, it is evident that these data are an important basis for palaeoenvironmental studies.

In every correlation exercise the diachroneity of the lithostratigraphic boundaries determines the discrepancy between lithostratigraphic correlation and time-correlation. Here it is shown that diachroneity varies in degree as a simple function of the direction in which correlation is made, and hence that stratigraphic correlation must take that direction into account. When the direction of correlation is not known, a sound strategy for time-correlation of lithostratigraphic boundaries is to assume that each is at its most diachronous.

The stratigraphy of the Hawasina Complex is redefined and rationalized to conform with standard stratigraphical nomenclature. Previously proposed tectono-stratigraphical units are abandoned in favour of a system that relies on the lateral correlation of lithofacies between structural units. To this end, the Dibba, Dhera, Wahrah and Al Ayn Formations are incorporated into an expanded Hamrat Duru Group. This group is divided into five formations, the Zulla, Guweyza Sandstone, Guweyza Limestone, Sid'r and Nayid and spans Triassic to Mid Cretaceous (Cenomanian) time. It locally passes up into the syn-orogenic sediments of the Riyamah Member of the Muti Formation. The nomenclature of the deeper-water, chert-dominated formations is left unaltered.

The belemnite genus Pseudohibolites Blüthgen, 1936 was erected without designation of a type species and is invalid according to Article 13b of the International Code of Zoological Nomenclature. The species P. nathorsti Blüthgen and P. caroli Blüthgen are reinterpreted using topotypes from Kong Karls Land and are considered species of Hibolithes Montfort, 1808.

The earliest skeletal microfauna of Precambrian-Cambrian age recovered from the ‘Lower Tal’ sequence (Chert-Phosphorite to Calcareous members) of the Tal Formation, exposed in the Ganga Valley, Lesser Himalaya, Uttar Pradesh, India, has been grouped into three assemblages. In ascending order these are: assemblage I, containing Anabarites trisulcatus Missarzhevsky, Tiksitheca korobovi (Miss.). Circotheca sp., Turcutheca sp., Spirellus columnorus Jiang and Olivooides alveus Qian; assemblage II, yielding Allonia erromenosa Jiang, A. sp. cf. A. erromenosa Jiang, Dimidia simpleca Jiang, D. sp. cf. D. simpleca Jiang and Hyolithellus sp.; and assemblage III, comprising Pelagiella lorenzi Kobayashi, Auriculatespira madianensis Zhou & Xiao and A. andunca He & Pei. The assemblages I and II are correlatable to the Meishucunian Zone I and Zone III respectively, and the assemblage III to the Qiongzhusian Stage of China. Thus the ‘Lower Tal’ sequence is assigned to Precambrian–Cambrian age.

SIR - Squire (1973) described and figured fossil burrows, ascribed to Sabellarites, from the Upper Proterozoic Brioverian Jersey Shale Formation of Jersey, Channel Islands. The meander-like structures are from calcisiltite beds within a turbiditic sequence and were collected from low intertidal reefs. Re-examination by all of us of one of Squire's specimens (Jersey Museum, La Hougue Bie, SJM C 2026; Squire, 1973, plate 1 a) and more decisive material (SJM C 1002, 5 specimens), collected later from the same reefs by Stéphane Rault, confirms that the structures are attributable to modern polychaetous annelids, almost certainly to Polydora sp., an attribution with which Dr J. D. George (Head, Polychaeta Section, British Museum (Natural History)) concurs. Polydora is associated with a wide range of substrate preference, constructing borings in hard calcareous substrates, pseudoborings on the inside of shells and true burrows in loose sediment. In the Jersey material the irregular, but quite typical, U-form tubes have been formed along open joint planes with slight dissolution of the rock, or along thin calcite-filled veins, also with dissolution of the rock. The joints occur at all angles to the bedding. Very pertinent is the attitude of the tubes, which is principally normal to the rock surface rather than to the bedding. No tubes have been seen on freshly broken surfaces and in no instance has a tube been seen to enter the rock, though there are numerous moulds of pyritic concretions which happen to be of about the same diameter as the width of the tubes. Lithothamnium sp. is patchily distributed over the rock surface and locally penetrates into the joints, showing that they were open.

The Geologists& Association has done a valuable service for British geology and for English-speaking geologists outside the British Isles by organizing field excursions and, for or from them, publishing guides. The first GA contribution was a report of a field meeting led by Gregory & Tyrrell (1924). In the 1960s there was a GA series of at least 41 guides covering most field areas in Britain and of these the one by S. I. Tomkeieff (1961) treated Arran. Tomkeieff's guide was brief and was not up to the standard expected of a work concerning this much frequented island. That work may be out of print and this guide appears to be a replacement. McKerrow & Atkins is good value and gives much to think about. Without hesitation, then, the reviewer's advice is that anyone going to Arran should buy it.