BROCKHOLES GEO TRAIL – RIBBLE VALLEY
Welcome to The Brockholes Geotrail
The Ribble Way provides a ready-made excursion into many of the geological landscapes of Lancashire and the Yorkshire Dales. These short geotrails provide a way of exploring them. A geological guide to the whole route is planned for the future.
The Ribble valley’s oldest rocks are sandstones and limestones which were laid down 410-510 million years (Ma) ago in the Ordovician and Silurian periods. They have been affected by folding and faulting during their long history. Around Horton-in-Ribblesdale and Stainforth these processes uplifted the older rocks to the surface, where today they are quarried for roadstone at Horton and Ingleton.
You can download the geotrail guide and background information below.
However, the trail guide is designed as an A3 document which folds down to A6. You will have to print it in sections if using an A4 printer.
Walk 2 – Background Information
The route of the Brockholes Geotrail does not encounter solid rock geology, but the Lancashire Wildlife Trust reserve owes its existence to the geological history of this part of the Ribble valley.
The glacial history of the area and the geomorphology of the Ribble valley are the key themes in this document.
The aim of this background material is to put Brockholes in its geological context, to relate the rocks which are to be found here to the stratigraphy and to link the geology of this area with that found elsewhere in the Geotrail series.
Figure 1. Stratigraphy of the Triassic, Permian and Carboniferous rocks which underlie Brockholes (British Geological Survey online time chart)
The British Geological Survey website gives the latest internationally agreed definitions of stratigraphy, together with dates in Ma (millions of years before present), as shown in Figure 1.
Nomenclature has changed in recent years so that Bunter Sandstone is now known as Sherwood Sandstone and Keuper Marl is now called Manchester Marl as the BGS strives to standardise the names of rock units.
The rocks beneath Preston and the Lancashire coast are of Middle and Lower Triassic age. Rocks of Permian age are absent at the surface in the county, while the older Carboniferous rocks form the surface rocks of upland Lancashire. The diagram below shows the relationships of these rock units.