The biostratigraphy of the upper part of the Mississippian Lower Limestone Formation in the Midland Valley, Scotland is revised using foraminiferal assemblages. This formation was previously assigned exclusively to the upper part of the Brigantian Substage (upper Cf6δ, P2 or latest Visean), whereas the succeeding Limestone Coal Formation (barren of foraminifers and conodonts) was assigned to the Pendleian Substage (lower Cf7, E1 or early Serpukhovian). The foraminifers, in particular those recorded from the Second Hosie and Top Hosie limestones and their lateral equivalents (Anvil and MacDonald limestones), are comparable to Serpukhovian assemblages from the Ukraine and Russia. Consequently, the Visean/Serpukhovian stage boundary is repositioned at the base of the Second Hosie Limestone. This assignment of the Second Hosie Limestone to the Pendleian is reinforced by the first occurrence of the ammonoid Emstites (Cravenoceras), although it occurs 1 m below the Top Hosie Limestone. Pendleian foraminiferal assemblages from northern England, its geographically closest equivalent, are similar but not well enough known for a detailed comparison. A few similarities are found between the foraminiferal assemblages from the Midland Valley and those from southwest Spain and North African basins. Faunas from the Second and Top Hosie limestones and their lateral equivalents allow us to propose an assemblage zone, valid for regional correlations within the British Isles, and the faunas can be potentially used as Serpukhovian markers for western Paleotethyan basins. Two new genera and species are described, Praeplectostaffella anvilensis n. gen. n. sp. and Praeostaffellina macdonaldensis n. gen. n. sp., and two new species, Tubispirodiscus hosiensis n. sp. and Euxinita pendleiensis n. sp.

Foraminiferal, algal and problematica assemblages from the Mississippian (late Viséan and early Serpukhovian) Lower Limestone Formation have been studied in order to validate lithostratigraphical correlations of limestones within the central and western parts of the Midland Valley of Scotland. Analysis of more than 100 outcrops allows recognition of four calcareous microfossil assemblages, which span the late Brigantian and early Pendleian, and enables a detailed correlation to be made within the Central Coalfield (north Lanarkshire) and with the thinner sequences to the west (north Ayrshire), to the south (Douglas area, south Lanarkshire), and to the east (Bathgate area, West Lothian). The age of the Lower Limestone Formation is modified because the upper part of this formation is now assigned to the Pendleian (due to the first occurrences of new foraminiferans and the co-occurrence with the Namurian goniatites), and some individual limestone horizons within the formation are repositioned, or their precise correlation with other limestones is established. A refined stratigraphical framework is proposed for the above noted areas, and a correlation between them and the Pennine region in northern England is proposed, passing through the Archerbeck Borehole sequence in the Scottish Borders.

Summary The paper presents a revised and detailed correlation of Yoredale limestones, from the Jew Limestone to the Great Limestone, from the Alston area across Northumberland into southern Scotland. Stratigraphical and micro-palaeontological evidence suggests that the Scar Limestone of Alston is the lateral equivalent of the “Five-Yard” Limestone of Greenhead and consequently of the Eelwell Limestone of north-east Northumberland. Lower in the sequence the Jew Limestone appears to split northwards into the Oxford and Barrasford limestones of Northumberland. Apart from a narrow area of thicker strata on the southern margin of the Northumberland Trough, the higher Yoredale beds in the trough do not exceed greatly in thickness those of the Alston Block.

Cornstones, concretionary limestones in the Scottish Upper Old Red Sandstone, are the limestone horizons in fossil calcareous soils (pedocals). The soil profile comprises three horizons; the topmost of red-bfown sand, the middle of black marl with small impure calcareous nodules, and the lowest of relatively pure limestone (the cornstone proper), often showing colour banding and oolitic structure. The cornstone may be up to 15 ft. thick, and was formed in situ by replacement of the detrital quartz and felspar grains of the parent sand by microcrystalline calcite. The Ayrshire cornstones seem to resemble closely the Pliocene caliche limestones of South-Central U.S.A..

The correlation of disparate mid- to late Viséan platform carbonate successions of the Great Scar Limestone Group across northern England formerly relied heavily upon a coral and brachiopod biozonation scheme erected in the early 20th century. This subsequently guided the development of a regional chronostratigraphic scheme some sixty years later that continues to be used to the present day, broadly coinciding with development of new lithostratigraphical nomenclatures, different for each distinct structural area. Correlation problems encountered within these lithostratigraphic units from study of their foraminiferal assemblages, as well as critical analysis of the stratotype sections for the Holkerian and Asbian substages, questions the veracity of the long-established coral and brachiopod biostratigraphy. This study appraises the lithostratigraphical and biostratigraphical relationships of late Arundian to late Asbian limestones across the Askrigg and Alston blocks, the Stainmore Trough and flanks of the Lake District Block. It considers the correlation and potential rationalisation of lithostratigraphic units, comments on revisions to the definition of the Holkerian and Asbian substage stratotypes and the suitability of the various biostratigraphical guide fossils.