The technique of laying large stone slabs direct on the ground to make a dry, durable surface is a simple and ancient technique, universally used for pavements and floors. In recent years this technique has been used on rural paths to solve the particularly difficult problem where popular paths cross deep peat. It has been found that if rectangular slabs or ‘flags’ are used, butted up to each other, they do not sink or move with use even in deep, wet peat. Even in the most difficult conditions, no geotextile or other sub-base is needed, as the suction of the wet peat holds the flag firmly in place. This technique has been made possible by the use of helicopter airlifts to get the stone on site, a method which is extremely efficient and cost-effective. The current availability of relatively low- cost slabs from demolition sites has also been a factor.
The flagstone paths have their critics, who find them intrusive and urban, as well as being quite hard on the feet. However, anyone familiar with the conditions on paths such as the Pennine Way at Snake Summit over the last decade would recognise that something had to be done to stop the damage and erosion. Of the many techniques tried over the years, the stone flag paths have the advantage of being effective, using only natural materials which do not leach or alter the surrounding flora, and being very quick to lay with the minimum of further damage to the ground. The flagstones being used on the Pennine Way are reclaimed flooring from redundant mills, brought by lorry to a nearby site, and then airlifted to the path.
Where flagstone paths have been laid, the old path lines will be visible for many years, but the general recovery of the vegetation is impressive. There are no plans to make a continuous flagstone path, but merely to cross the most damaged sections of deep peat, which will total for example about 10km of the 65km length of the Pennine Way in the Peak District.
The recycled sandstone flags from the mills of East Lancashire are about 1m square and 100mm thick,weighing about 250kg apiece. They are airlifted in a bundle of four or five, and set down along the line of the path. A powered barrow is airlifted to the site for local movement of stone alongside the path. A team of four or five people are needed for laying the path. Two prepare the ground by removing tussocks of vegetation and levelling the peat to form the base, and three people lay the stones. The biggest stones are used for the wettest sections. All stones are laid rough side up, which gives better grip. Slopes of up to 10 degrees are suitable for flagstone paths, and simple cut-off drains can be included as necessary, using broken flags.
Small ditches are crossed with simple clapper bridges, set on broken flags.
At the southern end of the Pennine Way at Grindsbrook Meadows, Edale, flagstone paths have recently been laid on mineral soil. The grass sward cannot withstand the level of trampling, and a wide, braided path had developed, across gently sloping ground. Various techniques including stone pitching were tried without success, as walkers continued to favour walking on the grass, making ‘trods’ on either side of the constructed path. The entire length of the path through the meadows is now laid with double-width flagstones, which together with a drainage ditch on the upper side that discourages walkers from stepping off, has solved the problem.
Where necessary, an excavator was used to dig a drainage ditch, the spoil being used to make a slightly raised bank on which the flags were laid. The slopes of the ditch were carefully profiled, and the whole area seeded. Small culverts were made under the path, as shown.
Quarried slab paths
Where reclaimed rectangular flagstones are not available, newly quarried slabs can be used on mineral soils or shallow, eroded peat over firm sub-grades. Their irregular size and shape make them unsuitable for use in deep peat. They are laid in a similar way to flags, interlocking as much as possible. Where gaps occur, greater than about 200 x 200mm, they are pitched with suitable stone to make a surface level with the slabs. Smaller gaps are packed with small stones and well compacted soil, and either turfed or seeded.
Slab and pitched stone paths
This is a further development by the Cleveland Way Project, for paths on slopes of between 5 and 10 degrees, with the pitched sections used to gain height, and to retain and stabilise the stone slab sections. The slabs are laid so their surface has a slope of 5 degrees or less, with each slab wedged firmly against the lower slab. The pitched sections cover between 10 and 50% of the mixed treatment length. Cut-offs or open stone drains are built as necessary in the pitched sections. Either reclaimed rectangular slabs, or irregular quarry slabs can be used, according to availability.
