Hard landscaping : Timeline Path at the BGS

Part of work being carried out at the Geological Survey in Nottingham is a pathway tracking the geological timeline of the stone of Britain, thanks to the contributions of British stone producers.

The British Geological Survey’s headquarters at Keyworth, near Nottingham, are being redeveloped and a geological timeline pathway constructed from the stone of the British Isles by UK based natural stone supply specialists CED Ltd is to be a central feature.

The pathway, first mooted by the BGS a decade ago, will include a variety of feature rocks and boulders from all over the UK, with the new entrance area and the path between the major buildings paved throughout in British stone.

BGS say it is a work in progress with some of the details still to be finalised. It will be another year before the work is completed but CED used their stand at the Street Design exhibition in March to give a preview of many of the materials that will be included, all laid out in their period sequence, as they will be in the Geological Survey’s pathway.

Currently commercially available stone technically suitable for paving will be included in the pathway, coming from many parts of the United Kingdom. There will even be a few materials that are no longer actively quarried.

The 1,200m2 geological pathway will go from the oldest to the youngest rocks, beginning at the Pre-Cambrian with Lewisian Gneiss, which has no paving representation in active production but some rocks in Scotland suitable for sawing are currently being selected.

The path will continue through the eras of geological time – the Cambrian, represented by Welsh slate, the Ordovician and Silurian with Cumbrian slates, the Devonian represented by both Cornish slate and Caithness flagstone, followed by varieties of Yorkstone and Pennant sandstones from the Carboniferous.

The sequence will continue with Permian and Triassic sandstones from Dumfriesshire and Morayshire, with Blue Lias and Purbeck limestones representing the Jurassic and Cretaceous periods, respectively.

The most recent rocks will be from the Cenozoic or Tertiary, represented by Mourne granite from Northern Ireland.

There being no rocks suitable for sawing from the latest and current Quaternary Period, some much older, sliced, rounded cobbles and beach pebbles, which were eroded and transported by rivers from melting glaciers in the Quaternary, will be included to complete the timeline.

Interspersed appropriately along the pathway are Cornish granites, reclaimed setts from Aberdeen and Peterhead, reclaimed ironstone setts originally from the sandpits south of London and knapped flints from the chalk of Essex..

Jurassic Portland limestone will be included in the form of a seat. A one metre wide spine running the length of the geological path will be in fine-grained Yorkstone.

The main entrance of nearly 600m2 will be set out in slate, Cumbrian and Welsh in tandem, with Caithness Flagstone dividing strips.

Britain has some highly competent paving stones and it will be wonderful to see them all set out, not just as exhibits but actively used.

The British Geological Survey is particularly keen for the rocks and boulders to showcase something of the remarkable variety of stone from the UK, which has incredible geological diversity within a relatively small area.

CED have been involved before in geological diversity – for the National Gardens of Wales, the Natural History Museum in London and Dynamic Earth in Edinburgh, among others. The company already have in stock or can obtain from readily available sources a good few of the stones needed.

The largest of the rocks will weigh close to 20 tonnes each. Lewisian Gneiss, the oldest rock type in the UK, will be the main feature rock at the entrance.

The geological path will include one large feature rock from each of the main countries of the UK. All will be quite spectacular, both in their geology and their sheer presence. Throughout the path will be smaller individual rocks displaying many specific geological characteristics. These examples will provide a much needed ready study facility for geology students.

The project for this second stage of the redevelopment of the site has been a long time in gestation. The management and geologists at the BGS were particularly keen to include displays of as many British paving stones as possible, but the cost barrier appeared insurmountable.

When BGS’s landscape architects, Munro & Whitten, started work they were constrained by costs to how much stone paving could be included. Life got harder still when they realised the difficulty of finding appropriate stone from each geological period, so, in May last year, CED were approached for help and have been the stone consultants since.

MD Michael Heap, long an exponent of the virtues of natural stone, found it difficult to hold back from saying that the whole of the path and the main entrance areas should be paved exclusively with stone.

Of course, if this not wholly pedestrian path is to be in use for many years, it needs to be laid on concrete and with the best mortar, which does also affect the price.

However, when the BGS was asked whether it would be prepared to make this path available to British stone producers as a permanent display for architects, landscape architects and designers generally to be able to view, they agreed with enthusiasm.

That enabled Michael to approach the British stone industry for their support, which has been enthusiastically given. No company is providing the stone free, but all the regular producers of paving are supplying at the same reduced price. And all those making ‘specials’ because the geology timeline continuity demanded it, are doing so at much reduced cost, for which everyone involved is extremely grateful.

Kier Marriott have fully entered into the spirit of achieving something exceptional on this design & build contract, as have architects Frank Shaw Associates, who are producing the detail setting out arrangements to use each stone in the way that that stone should be used.

Almost all the paving will be laid in courses with stone of random lengths to reduce waste and make the most efficient use of the raw material. The widths and thicknesses have been chosen for each stone with the same thinking but also, wherever possible, to make laying more economical.