The stratigraphy of the Siktefjellet and Red Bay groups of northwestern Spitsbergen is revised in the light of new fieldwork. An early Early Devonian (Lochkovian) age is indicated by the rich fossil vertebrate faunas of the Red Bay Group. The underlying Siktefjellet Group is likely to be Late Silurian in age, although there is no direct fossil evidence of this. The most abundant sediment type in the two groups is fine-grained fluvial sandstone, although conglomerates and lacustrine siltstones also occur. The conglomerates that predominate in the lowest parts of both groups imply the presence of fault scarps at the surface. There has been much debate about the importance of strike-slip faulting in the area, particularly in relation to the major north-south trending Raudfjorden and Breibogen faults. Between these faults, the Biskayerhuken-Holtedahlfonna terrane contains a zone for which the deliberately genetic name 'Siktefjellet Strike-slip Zone' is proposed. This zone is characterized by evidence for a succession of events that, taken together, suggest a history of continuing, repeated strike-slip. These events were: (1) the tectonism and metamorphism of the basement (Krossfjorden Group) and the emplacement of the highgrade Richarddalen Complex, (2) development of crush zones in the basement, (3) deposition of the Siktefjellet Group in two distinct basins (perhaps of pull-apart origin), (4) deposition of the Red Bay Group (first as discrete scarp-related conglomerates, and then as part of a more stable fluvial basin), (5) localized compressional deformation of the Siktefjellet and Red Bay groups. § Died while climbing in the High Himalaya, August, 1996. (3) Ben Nevis Formation [900 m] Fraenkelryggen Formation [750 m] Andréebreen Formation Princess Alicefjellet (conglomerate) Member (5) [500 m] Buchananhalvøya (sandstone) Member (4) [700 m] Rabotdalen (mudstone) Member (5) [100 m] Rivieratoppen Formation (6) Wulffberget (marble conglomerate) Member (6) [100 m] Konglomeratodden (polymict conglomerate) Member (6) [200 m] Siktefjellet Group (7) Albertbreen (sandstone) Formation (8) [1400 m] Lilljeborgfjellet (conglomerate) Formation (9) [400 m] Rabotpasset (breccia) Formation (9) [25 m] Red Bay Group

On the Scottish mainland the Great Glen fault (GGF) displaces the Emsian to Frasnian Orcadian Old Red Sandstone (ORS) by only 25–29 km dextrally but net post–ORS dextral offsets in Shetland are much larger (120 km total). Most of the displacement (15–20 km) Permian initiation of the Inner Moray Firth Basin. It probably occurred between Frasnian cessation of Orcadian extension and accompanied transpressional inversion of the Orcadian Basin in the mid-late Carboniferous and/or possibly the late Devonian. Devono-Carboniferous transtension may also have occurred. The earlier history of the GGF includes late Caledonian sinistral motion which must have ceased by the late Emsian.

No abstract

The discovery of probable tetrapod tracks in the Upper Old Red Sandstone of Easter Ross, N Scotland, lends credibility to 19th century claims of ‘reptilian’ footprints in these rocks. These are the only probable amphibian fossils known in the west European Devonian and are amongst the oldest anywhere.

We study composition-valued continuous-time Markov chains that appear naturally in the framework of Chinese Restaurant Processes (CRPs). As time evolves, new customers arrive (up-step) and existing customers leave (down-step) at suitable rates derived from the ordered CRP of Pitman and Winkel (2009). We relate such up-down CRPs to the splitting trees of Lambert (2010) inducing spectrally positive Lévy processes. Conversely, we develop theorems of Ray-Knight type to recover more general up-down CRPs from the heights of Lévy processes with jumps marked by integer-valued paths. We further establish limit theorems for the Lévy process and the integer-valued paths to connect to work by Forman et al. (2018+) on interval partition diffusions and hence to some long-standing conjectures.