The story of Caldonlow begins around 350 million years ago during the Carboniferous period. Thanks to the whims of continental drift, the North Staffordshire moorlands and the Peak District of Derbyshire were much further south than they are today, and the region was covered by a shallow tropical sea. Over millions of years, a layer of shells and coral slowly built up on the seabed, both formed from the calcium carbonate secretions of a variety of marine animals.

The creation of limestone

As there was little current to disturb these deposits, this layer was slowly compacted by additional layers of sediment, again over millions of years, to create limestone. If you remember your school chemistry, you'll know that chalk, marble and limestone are all calcium carbonate, each made under different conditions. Limestone is in fact almost pure calcium carbonate and as a result is very light in colour (hence the name White Peak, as opposed to the gritstone areas of the Dark Peak further north).

Quarries

In places like the White Peak, subsequent weathering, erosion and the ice age scoured away the softer topsoil leaving the limestone outcrops at or near the surface, which could then be readily quarried. And this is precisely what happened at Caldonlow Quarry, which at the height of the Industrial Revolution was yielding some 6,000 tons a week. The valuable limestone was transported on a tramway to the terminus of the Caldon Canal at Froghall, 3 miles (4.8km) to the west, and from there it was taken by barge to Stoke, Macclesfield and other canal-fed towns across the Midlands.

Then, as now, limestone had a great many uses. High-quality stone was used directly for building, while aggregate (crushed stone) was used for making roads. When calcium carbonate is heated, it leaves a deposit of calcium oxide or quicklime. Quicklime is even more useful than limestone. As a fertiliser it improves crop yields by reducing the acidity of soil, and it also reacts with the main impurities in iron ore to make iron and calcium silicate (or slag), which floats on top of the molten iron and is removed for use in road building.

A Site of Special Scientific Interest

At Froghall, the limestone was fired in massive kilns to produce quicklime to be shipped direct to customers. Today, the wharf and the lime kilns are long abandoned and the quarry at Caldonlow is much quieter than it was 150 years ago. It's now a designated geological Site of Special Scientific Interest and is dominated by the massive cement works at the start of the walk. It won't come as a surprise to learn that cement is a mixture of clay and quicklime.

From the road corner head east along the gravel track, walking away from Cauldon. At the first corner go straight on for a track along a small valley. Pass a barn on your right, go through a slot or swing gate and then take the right fork along a wide dirt track. Go through the second gate ahead of you and after 25 paces go right, through an overgrown area, for a small stile into a wide, sloping field. Carry on straight up the hill.

At the far top corner of the field, go through a gate and straight across the next field to a gap in the wall ahead. After the gap, head for the far left-hand corner of the next field and cross a stile onto the A52. Bear left for 100yds (91m), then turn right along the narrow metalled road past Weaver Farm. As the road veers to the left it meets a fence. Go right, back on yourself, up the hill towards a gate in the dry-stone wall.

After crossing the stile here keep following the dry-stone wall to your right. At the next gate continue in the same direction, with the wall to your left. At the end of this wall bear slightly right to join another wall on the right and follow it to the gate.

Before crossing the dry-stone wall ahead of you, go left for 100yds (91m) and then right over a stile, before making straight for the trig point. From the trig point retrace your steps to the stile, but instead of crossing it, head left across the field, making for the dry-stone wall at the bottom. Follow this wall all the way to Wardlow.

Continue as far as the A52 and go straight across, following a public footpath sign. Continue over the thistly plateau of this field to a stile.

Turn right, go over another stile and along a waymarked route through the narrow belt of trees. At the far end go ahead through newly planted trees. Cross the stile in the far right corner and go left between the fence and wall. At the second stile turn right and go down the field-edge to a stile. Go left for 100yds (91m) and then right along a trail through a narrow valley. At the bottom of the valley rejoin the main track to return to the start point.