Geological Survey of Northern Ireland

DR MARIE COWAN PGEO, MIOD, MRIA, DIRECTOR, GSNI

The Department for the Economy (DfE) has responsibility for the collection and collation of annual production and employment figures of the quarry industry in Northern Ireland. This is carried out under the Quarries (Northern Ireland) Order 1983. As the process runs a year in arrears, the most recent collated data are for the 2020 period, and the Annual Mineral Return for these data is published on the DfE website.

In recent years, partly driven by the local council development plan need for additional evidence to support mineral policies, additional questions have been asked on the annual return form. Some of these questions are aimed at ・ Providing a better picture of where extracted material is produced, ・Material movement across Northern Ireland (and beyond) and ・How local councils are dependant on neighbours and producers across Northern Ireland as a whole.

Part of this process has involved developing a method that makes the information more accessible and easier to understand, rather than simply producing more tables of numbers as in the current annual mineral return documents. The diagram (Figure 1) below is an attempt to address this. Sankey diagrams were developed by Irish Captain, Matthew Sankey, who used this type of diagram in 1898 to show the energy efficiency of a steam engine. Originally used to show the flow of a single entity, the technique can be developed by using different colours to represent different parts of a system allowing various material flows to be visualised. In the image shown, the colours are based on simplified Geological Survey of Northern Ireland bedrock map colours; red for igneous rock, blue for limestone, green for sandstone (gritstone) and orange for sands and gravel. The thickness of the lines represents the proportional amount of material produced, initially from Northern Ireland as a whole on the left of the image and in what proportions they are extracted in each of the district council areas on the right of the image. For example, sandstone (green) is the only material reported for Ards and North Down for the 2020 period whereas Mid Ulster, although dominated by sand and gravel (orange), also has reported production of the other primary materials. It is important to remember when considering this diagram (and the mineral return as a whole) that the information presented is as submitted by the industry. In any situation where there has not been a return from a particular operator for the reporting period, that data will (obviously) be missing. This is not considered a major issue when dealing with the bulk extraction from the country as a whole, as illustrated in the image. There is greater impact when reporting at specific district council level, where the data are needed to help inform the development plans. The annual mineral return remains an indispensable central information gathering exercise. Its value is recognised by the MPANI in communicating the essential need of mineral extraction across the whole of Northern Ireland. The ongoing support of the industry in providing the detail for the annual mineral return will maintain the profile of this key industry.

Dr Marie Cowan