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Why limestone dales feel different

Walk into a limestone dale and the landscape changes character within a few hundred metres. The ground underfoot turns pale and grippy, the valley sides steepen into grey crags, and the woodland thins into ash, wych elm and hazel clinging to thin soils. The rock is Carboniferous limestone, laid down in warm shallow seas roughly 340 million years ago and then lifted, cracked and slowly dissolved by rainfall that is very slightly acidic. Dissolution, rather than the grinding of ice, is what gives these valleys their distinctive shape.

The result is a landscape of hard edges and hidden hollows: sudden gorges, dry valleys, springs that appear out of nowhere and streams that disappear into the ground. Once you can read those features, a walk that looks unremarkable on the map becomes a lesson in how water and rock negotiate with one another over millennia.

Gorges, dry valleys and the work of water

Many limestone gorges began as meltwater channels at the end of the last ice age, when enormous volumes of water poured off frozen ground and cut steep-sided notches through the rock. Later, the streams found easier routes underground, leaving the gorges partly or wholly dry. That is why you can walk along the floor of a deep, echoing ravine in August and hear nothing but the wind.

Look out for:

• Dry valleys with a broad, rounded profile and no stream at the bottom — the water now flows through a cave system beneath your feet.
• Resurgences, where a river reappears at the foot of a cliff after travelling underground, often startlingly cold and clear.
• Scree slopes of shattered limestone below crags, loose and best avoided on steep ground.
• Stepping stones and clapper bridges, traditional crossings that mark old packhorse and farm routes through the dales.

The dry stone walls and small stone barns that thread these valleys are part of the same story. Limestone splits cleanly into usable blocks, so the walls are built from what the fields provided.

Limestone pavement: clints, grykes and the plants that hide there

Above the valley sides you may meet limestone pavement, one of the most extraordinary habitats in Britain. It looks like a cracked paving slab on a grand scale: flat blocks known as clints, separated by deep fissures called grykes. The pattern was formed by water dissolving joints in the rock, and it can be centuries old.

The grykes are cool, damp and sheltered, and they act as a refuge for plants that would otherwise struggle on exposed upland plateaus. Hart's-tongue fern, baneberry, wood anemone and dog's mercury all shelter in them, while the clint tops support limestone grassland with rock rose, wild thyme, bloody crane's-bill and, in the right places, orchids.

This is a genuinely fragile surface. The soil in a gryke may be only a few centimetres deep and has taken a very long time to accumulate. Walking on the clints themselves, or along the edges of the grykes, compacts and erodes them. Where a path exists, use it. Where it doesn't, pick your way along the rock edges rather than cutting across the middle of a pavement, and keep dogs close.

Caves, sinkholes and what lies beneath

Beneath the dales runs an unseen network of caves, swallets and underground rivers. A swallet is where a stream sinks into the ground; a shakehole or sinkhole is a hollow where the surface has collapsed into a void below. Both can be concealed by grass and bracken, which is why it pays to keep your eyes on the ground when crossing open limestone plateau.

Caves are fascinating but should not be entered casually. They are dark, cold, often flooded and prone to sudden water-level changes after rain. Many entrances are gated to protect roosting bats, which are legally protected, and to prevent damage to delicate formations. Enjoy them from the entrance, or go underground with proper equipment, a helmet, a lamp and someone who knows the system.

Walking safely and lightly in fragile ground

Limestone country is rarely dangerous, but it has its own habits. Wet limestone is slippery, and polished rock near popular viewpoints can catch out the unwary. Edges above gorges are often unfenced. Weather can change quickly on exposed plateau, and mobile signal is patchy in the deeper valleys.

• Carry a paper map and compass as well as a phone. Footpaths across open access land can be faint on the ground.
• Check access status before you go. Much upland limestone is open access land under the right to roam, but some areas are closed at certain times, and footpaths and permissive routes vary. Signs and stiles are there for a reason.
• Wear boots with a decent tread and pack a waterproof; the rock drains fast but the valleys can be humid and cold.
• Give livestock and ground-nesting birds space. Keep dogs on a lead around sheep and cattle, and between March and July on open moorland.
• Leave no trace. Take litter home, don't build cairns, and never chip or collect rock, fossils or plants.

Planning a good day out

The classic limestone dales of the Peak District, the Yorkshire Dales and the Mendips all reward a slow, curious approach. Plan a route that follows a valley floor, climbs to a pavement or viewpoint, and returns by a different line, so you see the landscape from both below and above. Allow more time than the distance suggests — you will want to stop, look at the grykes, and listen for water running underground.

Walk gently, and these dales will keep revealing themselves, season after season, in the detail of a fern in a crack or the cold blue of a spring rising from the rock.