OR/16/053 Introduction

Ellen, R, Callaghan, E, Leslie, A G, and Browne, M A E. 2016. The rocks of Spireslack surface coal mine and its subsurface data: an introduction. Nottingham, UK, British geological Survey. (OR/16/053).

Spireslack is an abandoned surface coal mine (SCM) at Glenbuck, East Ayrshire, Scotland. The Carboniferous Limestone Coal Formation was mined here for its extensive and thick coal seams: indeed, it is one of the main coal producing units in the Midland Valley of Scotland. The Glenbuck area has a long history of mining beginning with bell pits sunk for ironstone in the late 18th century. Underground coal extraction was active in the late 19th/early 20th century followed by later 20th to 21st century surface coal mine operations. Underground coal mining within the Spireslack area was accessed via the Grasshill Pit, which closed in 1931 and presaged the final decline of Glenbuck village — of which there is little trace today. Surface coal mining began around 2000, ending in 2008 due to the decline of the Scottish coal industry.

As a result of the surface coal mining, the main void at Spireslack has created a spectacular worked face 1 km long and 130 m high, which exposes almost the entirety of the Limestone Coal Formation. Worked faces elsewhere across the site expose sequences from the Lawmuir, Lower Limestone and Upper Limestone formations (Figure 2). The geological structures and strata exposed here are not typically seen on anything approaching the same scale or completeness/continuity within natural sections across Scotland, or farther afield in the UK. Spireslack also preserves evidence of the earlier generation of mining, where 20th/21st century surface mine operations are superimposed on underground workings from the 19th/20th century.

Though the coal mines throughout the Glenbuck region were abandoned with no resources available for ground restoration, the current owners, SMRT (Scottish Mines Restoration Trust) are currently investigating solutions for the orphaned sites. BGS are assisting in this task: a geodiversity audit of the Spireslack surface coal mine was completed by BGS in 2015 (Ellen and Callaghan, 2015), with a follow up audit of the neighbouring Ponesk and Grasshill SCMs in 2016 (Ellen and Callaghan, 2016). BGS have also invited a number of UK universities to Spireslack, and a number of research projects focussed on the site are gathering momentum.

This report firstly provides an account of the geology exposed at Spireslack, based on a number of field visits made over the course of 2014/2015 plus past visits by BGS dating back to 2002. This report is therefore intended as an overview of the geology at the site, and as an foundation document for future research and education on the site. Secondly, the report presents results of a 3D geological model of the Spireslack area, constructed using legacy mining data collected over the last two centuries. This model is intended to underpin future geological investigations at Spireslack and to aid in a broader understanding of the region’s geology.