ABSTRACT In Scotland, the base of the Ballagan Formation has traditionally been placed at the first grey mudstone within a contiguous Late Devonian to Carboniferous succession. This convention places the Devonian–Carboniferous boundary within the Old Red Sandstone (ORS) Kinnesswood Formation. The consequences of this placement are that tetrapods from the Ballagan Formation were dated as late Tournaisian in age and that the ranges of typically Devonian fish found in the Kinnesswood Formation continued into the Carboniferous. The Pease Bay specimen of the fish Remigolepis is from the Kinnesswood Formation. Comparisons with its range in Greenland, calibrated against spores, show it was Famennian in age. Detailed palynological sampling at Burnmouth from the base of the Ballagan Formation proves that the early Tournaisian spore zones (VI and HD plus Cl 1) are present. The Schopfites species that occurs through most of the succession is Schopfites delicatus rather than Schopfites claviger . The latter species defines the late Tournaisian CM spore zone. The first spore assemblage that has been found in Upper ‘ORS' strata underlying the Ballagan Formation (Preston, Whiteadder Water), contains Retispora lepidophyta and is from the early latest Famennian LL spore zone. The spore samples are interbedded with volcaniclastic debris, which shows that the Kelso Volcanic Formation is, in part, early latest Famennian in age. These findings demonstrate that the Ballagan Formation includes most of the Tournaisian with the Devonian–Carboniferous boundary positioned close to the top of the Kinnesswood Formation. The Stage 6 calcrete at Pease Bay can be correlated to the equivalent section at Carham, showing that it represents a time gap equivalent to the latest Famennian glaciation(s). Importantly, some of the recently described Ballagan Formation tetrapods are older than previously dated and now fill the key early part of Romer's Gap.
ABSTRACT The lower Mississippian Ballagan Formation of northern Britain is one of only two successions worldwide to yield the earliest known tetrapods with terrestrial capability following the end-Devonian mass extinction event. Studies of the sedimentary environments and habitats in which these beasts lived have been an integral part of a major research project into how, why and under what circumstances this profound step in the evolution of life on Earth occurred. Here, a new palaeogeographic map is constructed from outcrop data integrated with new and archived borehole material. The map shows the extent of a very low-relief coastal wetland developed along the tropical southern continental margin of Laurussia. Coastal floodplains in the Midland Valley and Tweed basins were separated from the marginal marine seaway of the Northumberland–Solway Basin to the south by an archipelago of more elevated areas. A complex mosaic of sedimentary environments was juxtaposed, and included fresh and brackish to saline and hypersaline lakes, a diverse suite of floodplain palaeosols and a persistent fluvial system in the east of the region. The strongly seasonal climate led to the formation of evaporite deposits alternating with flooding events, both meteoric and marine. Storm surges drove marine floods from the SW into both the western Midland Valley and Northumberland–Solway Basin; marine water also flooded into the Tweed Basin and Tayside in the east. The Ballagan Formation is a rare example in the geological record of a tropical, seasonal coastal wetland that contains abundant, small-scale evaporite deposits. The diverse sedimentary environments and palaeosol types indicate a network of different terrestrial and aquatic habitats in which the tetrapods lived.
Extensive evaporites in Lower Mississippian successions from palaeoequatorial regions are commonly used as evidence for an arid to semi‐arid palaeoclimate. However, in this article, detailed studies of evaporites and their context refute this interpretation. Detailed sedimentological and petrographical analysis of the Lower Mississippian of northern Britain, is combined with archived log data from more than 40 boreholes across southern Scotland, northern England and Northern Ireland, and published literature from Canada. Two key cores from the Tweed Basin and the northern margin of the Northumberland – Solway Basin contain 178 evaporite intervals and reveal twelve distinct forms of gypsum and anhydrite across seven facies that are associated with planar laminated siltstone and intercalated thin beds of ferroan dolostone. Nodular gypsum and anhydrite, typically in intervals <1 to 2 m thick, are integral components of the succession. Nodular evaporite occurs within about 1 m of a palaeosurface, but most evaporite deposits represent ephemeral brine pans to semi‐permanent hypersaline lakes or salinas on a floodplain that was subjected periodically to storm surges introducing marine waters. Formation of evaporites under a strongly seasonal climate in a coastal wetland is supported by palaeosol types and geochemical proxies, and from palaeobotanical evidence published previously. Although 65% of modern equatorial areas experience a strongly seasonal climatic regime, salinas and sabkhas are a minor component today in comparison with the evidence from these Lower Mississippian successions. This implies that the earliest terrestrial environments were complex and dynamic, providing a diverse range of habitats in which the early tetrapods became terrestrialized and represent a setting that is rarely preserved in the geological record.
The Visean stage of the Mississippian was a time of rapid tetrapod diversification which marks the earliest appearance of temnospondyls, microsaurs and the limbless aistopods. Tetrapod finds from this stage are very rare and only a dozen sites are known worldwide. Here we announce the discovery of a new Visean site in Fife, Scotland, of Asbian age, and from it describe a new species of the baphetoid Spathicephalus. These specimens represent the oldest known baphetoid by three million years, yet belong to themost specialized members of the clade. Unlike typical baphetoids with large marginal teeth and palatal fangs characteristic of early tetrapods, spathicephalids had very broad flattened heads with a dentition consisting of a large number of small, uniform teeth. Spathicephalids were probably one of the earliest tetrapod groups to use suction feeding on small, aquatic prey. Palynological and sedimentological analysis indicates that the new fossil bed was deposited in a large, stratified, freshwater lake that became increasingly saline.
The recent economic collapse of the opencast surface coal mining industry in the Midland Valley of Scotland has left behind a number of abandoned voids that reveal stunning 3D exposures in strategically important strata. A strong case can be made for retaining these large-scale, often continuous and very detailed geological sections that might otherwise have been lost to us, along with their relevant digital geological and geotechnical datasets and other social and industrial records. In particular, Spireslack and Mainshill Wood opencast workings might be seen by some as industrial scars on the Scottish landscape, but they can instead both be turned into national assets for multidisciplinary Geoscience research and learning in general, supporting high-quality international research into Carboniferous geology. Such opencast sites can also provide a rich visitor and/or learning experience for the wider public in coal geology, illuminating aspects of a former way of life of previous generations.
The Lower Mississippian (Tournaisian) Ballagan Formation in SE Scotland yields tetrapod fossils that provide fresh insights into the critical period when these animals first moved onto land. The key to understanding the palaeoenvironments where they lived is a detailed analysis of the sedimentary architecture of this formation, one of the thickest and most completely documented examples of a coastal floodplain and marginal marine succession from this important transitional time anywhere in the world. Palaeosols are abundant, providing a unique insight into the early Carboniferous habitats and climate.More than 200 separate palaeosols are described from three sections through the formation. The palaeosols range in thickness from 0.02 to 1.85 m and are diverse: most are Entisols and Inceptisols (63%), indicating relatively brief periods of soil development. Gleyed Inseptisols and Vertisols are less common (37%). Vertisols are the thickest palaeosols (up to 185 cm) in the Ballagan Formation and have common vertic cracks. Roots are abundant through all the palaeosols, from shallow mats and thin hair-like traces to sporadic thicker root traces typical of arborescent lycopods.Geochemical, isotope and clay mineralogical analyses of the palaeosols indicate a range in soil alkalinity and amount of water logging. Estimates of mean annual rainfall from palaeosol compositions are 1000-1500 mm per year. The high mean annual rainfall and variable soil alkalinities contrast markedly with dry periods that developed deep penetrating cracks and evaporite deposits. It is concluded that during the early Carboniferous, this region experienced a sharply contrasting seasonal climate and that the floodplain hosted a mosaic of closely juxtaposed but distinct habitats in which the tetrapods lived. The diversification of coastal floodplain environments identified here may link to the evolution and movement of tetrapods into the terrestrial realm. (C) 2016 The Authors. Published by Elsevier B.V. All rights reserved.
The Nature Conservancy Council Earth Science Conservation Strategy (1990) had six main areas for action, including maintaining the Special Sites of Scientific Interest (SSSI) series through the Geological Conservation Review and expanding the Regionally Important Geological/Geomorphological Sites Network (now Local Geodiversity Sites; LGS). Protection of SSSI's is well understood, statutory and the planning system generally sympathetic, albeit with a few recent notable exceptions. Local Geodiversity Sites protection is achieved through local planning policy. However, the establishment of a geodiversity site system and recognition of LGS is patchy in Scotland. Many local authorities still do not have policies to conserve their local geodiversity or to give it consideration in planning. Even where LGS have been recognised, damage to sites can occur because of lack of consultation following emergency incidents. A petition in 2009 was raised unsuccessfully in the Scottish Parliament to establish a Scottish Geodiversity Duty in order that an integrated approach to geodiversity and its conservation might be achieved. The Scottish Geodiversity Forum was established in 2011 and has pursued the avenues opened by the petition and a key Scottish Natural Heritage Report. The outcome is the launch of Scotland's Geodiversity Charter and active participation in the revision of the Scottish Biodiversity Strategy.
The Mississippian Strathclyde Group of the Midland Valley of Scotland yields some of the earliest non-marine ostracods. The succession records shallow marine, deltaic, estuarine, lagoonal, lacustrine, fluvial and swamp environments representing a series of staging-posts between fully marine and limnetic settings. Macrofossils and ostracods are assigned to marine, marginal marine, brackish and freshwater environments based on their faunal assemblage patterns. Key brackish to freshwater ostracods are Geisina arcuata, Paraparchites circularis n. sp., Shemonaella ornata n. sp. and Silenites sp. A, associated with the bivalves Anthraconaia, Carbonicola, Cardiopteridium, Curvirimula, Naiadites, the microconchid 'Spirorbis', Spinicaudata and fish. Many Platycopina and Paraparchiticopina ostracods are interpreted as euryhaline, which corresponds with their occurrence in marine to coastal plain water bodies, and supports the 'estuary effect' hypothesis of non-marine colonization. The success of non-marine colonization by ostracods was dependent on the intrinsic adaptations of ostracod species to lower salinities, such as new reproductive strategies and the timing of extrinsic mechanisms to drive non-marine colonization, such as sea-level change. The genus Carbonita is the oldest and most common freshwater ostracod, and went on to dominate freshwater environments in the Late Palaeozoic.
Integrating geodiversity into the planning system: An example from west Lothian, Scotland H. Barron. S. Arkley & M. Browne Bntish Geological Survey, Murchison House. West Mains Road, Edinburgh EH9 3LA, Scotland, UK Keywords: Geodiversity, protected sites, planning, Scotland West Lothian's Carboniferous bedrock and superficial deposits display a variety of Earth heritage features set within a varied landscape. In the first project of its kind in Scotland, this local geodiversity was audited by the British Geological Survey (BGS) in partnership with West Lothian Council (WLC), Scottish Natural Heritage (SNH) and Borders RIGS Group (LaBRIGS). The main objectives of the audit were to: initiate Scottish geodiversity auditing and action planning and act as a guide to further work in other areas of the country; allow incorporation of geodiversity into the development planning system along side and through integration with the Local Biodiversity Action Plan process, and; guide thee sustainable management, conservation and interpretation of all aspects of the Earth heritage of West Lothian. A total of 51 sites were selected as West Lothian Geodiversity Sites (WLGS) to complement and expand the existing network of four nationally designated sites (SSSls) and five locally protected sites (RIGS). Key benefits of protection and enhancement of local geodiversity include: Enhancement of local biodiversity Enhance understanding of historical, cultural and social significance of local earth resources Recreation and green space provision and enhancement Educational and scientific value Potential economic development through tourism by linking geodiversity with cultural history, wildlife and archaeology Together, BGS, WLC, SNH and LaBRIGS will set up Scotland's first LGAP partnership, implement the West Lothian LGAP, and produce geodiversity best-practice guidance for planners. For European Geoparks, a geodiversity audit is a very useful tool for Geopark development.