Robin A. Cullingford

Patterns of isostatic land uplift during the Holocene: evidence from mainland Scotland

Preliminary results of a lengthy and detailed investigation into middle- and late-Holocene raised shorelines in mainland Scotland indicate that three shorelines are sufficiently widely distributed to permit an examination of their extent and of the patterns of uplift which they indicate. The shorelines are the Storegga Tsunami Shoreline, reached at c. 7100 14C years BP, at the culmination of the Main Postglacial Transgression; and the Blairdrummond Shoreline, reached after the Main Postglacial Shoreline, at c. 2000–4200 14C years BP, at the time of a tsunami believed to have been caused by the Second Storegga submarine slide; the Main Postglacial Shoreline, reached at c. 5800–6850 14C years BP. The Main Postglacial Shoreline, previously believed to be the highest Holocene raised shoreline in Scotland, is now believed to be overlapped around the periphery of the uplifted area by the later Blairdrummond Shoreline. Isobase models, based upon quadratic trend surface analysis of available comparable height data consisting of altitudes on former estuarine surfaces and related to the local High Water Mark of Ordinary Spring Tides, depict the pattern of uplift for each shoreline. These models are probably more accurate than previous models of land uplift for the period studied, and indicate a consistent and unchanging uplift pattern during the middle and late Holocene.

A Major Coastal Flood During the Holocene in Eastern Scotland

Gehobene holozane astuarine Ablagerungen der postglazialen Haupttransgression enthalten in einer Anzahl von Fundpunkten an der Ostkuste Schottlands eine charakteristische Schicht vorwiegend aus grauem, glimmerfuhrendem Feinsand. Dort wo die Sedimente sich landseitig mit den ehemaligen Kustenmooren verzahnen, bilden sie im Torf spitz auslaufende Lagen, und auch hier tritt der graue, glimmerfuhrende Feinsand als spitzer Sedimentkeil auf. Diatomeenanalysen deuten auf einen marinen Ursprung hin, Pollenanalysen zeigen eine fruh- bis mittelatlantische Florenvergesellschaftung an und C14-Analysen von Torf aus dem oberen und unteren Kontakt deuten auf ein Ereignis von relativ kurzer Dauer um 7000 v. h. Gegenwartig wird angenommen, das die Lage entweder auf eine kurzfristig erhohte Rate des relativen Meeresspiegel-Anstiegs oder auf eine Sturmflut ungewohnlichen Ausmases zuruckzufuhren ist.

Towards improved empirical isobase models of Holocene land uplift for mainland Scotland, UK

A new approach to modelling patterns of glacio-isostatic land uplift during the Holocene in mainland Scotland, UK, is described. The approach is based upon altitude measurements at the inner margin or locally highest point of raised estuarine surfaces dated by radiocarbon assay supported by microfossil analyses. 2241 altitudes have been analysed by a technique new to studies of former sea-levels, Gaussian Trend Surface Analysis, and isobase models for four Holocene shorelines: the Holocene Storegga Slide tsunami shoreline, abandoned rapidly circa 7900 sidereal years BP; the Main Postglacial shoreline, abandoned during circa 6400–7700 sidereal years BP; the Blairdrummond shoreline, abandoned during circa 4500–5800 sidereal years BP, and a speculative fourth shoreline, the Wigtown shoreline, abandoned during circa 1520–3700 sidereal years BP, are shown in a series of maps. The implications of the shoreline patterns for glaicio-isostasy in the area are discussed. It is maintained that the statistical technique used enables broad estimates to be made of nearshore sea surface change.

The altitude and age of the main postglacial shoreline in Eastern Scotland

Abstract This paper discusses the patterns of altitude and age variation of the Main Postglacial Shoreline in eastern Scotland from the Firth of Forth to the Dornoch Firth. For reasons of comparability, attention is confined to the carseland areas. The mean altitude of the shoreline declines eastwards from 14.8 m to 6.1 m OD in the Forth area, from 11.2 m to 8.1 m in the Earn-Tay area, and northwards up the coast from the Tay area to ca. 6.4 m in the Montrose Basin area, ca. 3.9 m around the Ythan estuary and ca. 2.0 m near Fraserburgh. In the Beauly Firth/inner Moray Firth area it declines northeastwards from ca. 9 m to 7.1–7.9 m, and declines to 5.7 m in the Dornoch Firth. The isobase pattern for eastern Scotland, as represented by a quadratic trend surface, conceals a significant regional variation in the Tay area. The age of the shoreline has been investigated at 14 sites grouped in 8 locations at varying distances from the centre of uplift. The ages range from ca. 6800 14C years BP in the upper Forth carselands to 6095 ± 75–5700 ± 90 BP near Fraserburgh. With the exception of one site, the data are consistent with the hypothesis that the shoreline is measurably diachronous, having been abandoned progressively later with increasing distance from the centre of uplift. The implications of these findings for understanding isostatic-eustatic relationships are discussed.

Flandrian relative sea‐level changes in the Montrose basin area

Abstract Relict shore features and deposits of Flandrian age in the Montrose Basin area are examined. The main features are the former estuarine mudflats of the carselands surrounding the Basin and a complex of sand and shingle ridges lying to seaward. These features are thought to have accumulated as a result of the Main Postglacial Transgression in the area. During the transgression, a storm surge which took place at about 7000 years B.P. resulted in the deposition of a widespread layer of grey micaceous silty fine sand in the carse deposits. The culmination of the transgression is marked by an extensive carseland surface, which attains circa + 6.0m to + 7.0m, O.D. and by continued accumulation of the sand and shingle ridge complex, which reaches + 10.0m, O.D. As relative sea level fell subsequently, a second surface was produced, attaining circa + 4.0m to + 5.0m, O.D. in the carselands and up to + 5.8m, O.D. in the sand and shingle ridge complex. The wide extent of this feature in the latter area is pr...

Holocene relative sea levels and coastal changes in the lower Cree valley and estuary, SW Scotland, U.K.

Changes in Holocene (Flandrian) relative sea levels and coastal geomorphology in the lower Cree valley and estuary, SW Scotland, are inferred from detailed morphological and stratigraphical investigations. A graph of relative sea level changes is proposed for the area. Rising relative sea levels during the early Holocene were interrupted at c . 8300–8600 14 C years B.P.( c . 9400–9900 calibrated years B.P.), when an extensive estuarine surface was reached at c . −1 m O.D., after which a fluctuating rise culminated at c . 6100–6500 14 C B.P. ( c . 7000–7500 calibrated years B.P.) in a prominent shoreline and associated estuarine surface measured at 7·7–10·3 m O.D. A subsequent fall in relative sea level was followed by a rise to a shoreline at 7·8–10·1 m O.D., exceeding or reoccupying the earlier shoreline over much of the area after c . 5000 14 C B.P. ( c . 5,800 calibrated years B.P.), before relative sea level fell to a later shoreline, reached after c . 2900 14 C B.P. ( c . 3100 calibrated years B.P.) at 5·5–8·0 m O.D., following which relative sea levels fell, ultimately reaching present levels. During these changes, a particular feature of the coastline was the development of a number of barrier systems. The relative sea level changes identified are compared with changes elsewhere in SW Scotland and their wider context is briefly considered.

Holocene relative sea-level change in the lower Nith valley and estuary

Synopsis Detailed morphological, lithostratigraphical and biostratigraphical studies in the lower Nith valley and estuary, Scotland, disclose evidence for changing relative sea levels during the Holocene. The Main Postglacial Transgression was in progress in the area around c. 7500 14C years bp (8350 cal. years bp) to c. 7800 14C years bp (c. 8600 cal. years bp), perhaps by c. 7675 14C years bp (c. 8490 cal. years bp); relative sea levels fell briefly after c. 7200 14C years bp (c. 8020 cal. years bp); then resumed their rise after c. 7000 14C years bp (c. 7800 cal. years bp) and culminated by c. 590014C years bp (c. 6720 cal. years bp) reaching the Main Postglacial Shoreline, the evidence for which is widespread in the lower Nith valley. Subsequently, relative sea levels may have fluctuated, modifying or exceeding Main Postglacial Shoreline features along the estuary coastline before falling to a lower shoreline and then falling farther to reach present levels at c. 1760 14C years bp (c. 1800 cal. years bp), after which there is no evidence for relative sea-level change in the area. This sequence is considered broadly comparable with sequences recorded at other sites along the northern shore of the Solway Firth, in particular confirming evidence for a fluctuation in the Main Postglacial Transgression and for the age of the Main Postglacial Shoreline.