The rock is deeply fissured, and water vanishes suddenly and reappears miles away. This is why the approach from Malham village, past the spectacular limestone cliff of Malham Cove is such an eerie landscape. Before the ice age the River Aire filled the valley and careered over the cliff in a great waterfall.
The farming landscape of miles of ancient dry-stone walls, field barns, meadows and pockets of woodland creates a special beauty.
Malham Tarn is the only limestone lake in the country and is the highest freshwater lake of its size in England.
The Tarn lies on a bedrock of Silurian Slate in a depression scoured out by glacier ice in the Ice Age.
The 150 acre natural lake was once owned by the monks of Fountains Abbey, but is now owned by the National Trust.
The Pennine Way skirts the east end of the tarn, and then continues over the high ground to the north.
A few hundred yards from leaving the tarn, the river mysteriously vanishes through deep fissures in its limestone bed at a place called Water Sinks.
The Tarn and the surrounding wetlands are of internationally important scientific interest with a National Nature Reserve, a Ramsar site and three SSSI's.
The mixture of limestone cliffs, the acid 'raised bog', the alkaline fen and the nutrient-rich shallow lake make it a wonderful place for plants and wildlife.
There is an astonishing variety of plant and animal habitats for the altitude, from woodlands and grasslands to a fascinating complex of wetlands and open water.
Great-crested grebe, common sandpiper and coot breed on the shores of the tarn, which is stocked with brown trout.
The variety of limestone hills, farmland, wetlands and the Tarn make this an astounding area to visit, of great scientific interest.
