Malham Tarn

I was shocked to realise that it's eight years since I last went to Malham Tarn, which is surprising given how often I've been to Malham itself. It's not really far from the village, up beyond Malham Cove, but the landscape is bleaker: moorland and sheep pastures. During the 18th century the surrounding area was mined for lead and copper, and there are a few remnants from that time, including a smelt mill flue chimney. It is, however, a very peaceful landscape nowadays. 

The tarn itself is something of a rarity, the highest marl lake in the UK, at 1237 ft above sea level. Water rarely stays above ground in these porous limestone areas but the lake was carved out by a glacier in the ice age, which scraped down to an underlying slate layer and then, as the ice melted, dropped glacial moraine to effectively seal off the lake. It drains via a small stream (photo below) that then disappears underground. When the water resurfaces beyond Malham it forms the source of the River Aire. 

It is now in the care of The National Trust, which until recently leased out Tarn House (on the far shore, below) as a Field Studies Centre, though that may now have closed. The area is a National Nature Reserve, and the circular walk round the lake and through the peat bog on a boardwalk is a really lovely and quite gentle (flat) walk.