The Natural History of Upper Teesdale edited by Steve Gater (£9.50, Durham Wildlife Trust)

RARELY can the broad sweep of history be better seen than in Upper Teesdale, and this book charts its changes over 500 million years.

It tells how the rocks were created through pressure and fire, which gives them unique characteristics which in turn allows a unique set of plants to flourish upon their soils. It tells how Ice Ages came and went, sketching out the landscape, and then, finally, man arrived in surprisingly large numbers to seek out the minerals that could be found between the layers of the rocks.

Briefly, Teesdale’s oldest rocks were formed about 480m years ago when they were seabed south of the equator. About 420m years ago, tectonic plates collided, squeezing the sand on the seabed into sandstone, and then baking it with volcanic eruptions – the Pennines are set on a bed of Weardale Granite that cooled about 399m years ago.

Perhaps most importantly, about 295m years ago, there was a burst of magma – molten rock at 1,100 degrees C – up from the earth’s core. It didn’t burst out onto the surface, but cooled and crystallised between the layers so that it formed the distinctive Whin Sill, over which High Force now tumbles. That burst of magma also cooked the rocks it touched so that they changed into minerals and ores.

Then, about 60m years ago, it was all shifted and scrunched into place at the top end of the dale, only for millennia of ice ages to rub and gouge over the top of it.

When the ice retreated about 12,000 years ago, this part of the world was left with a wet and cool climate, and a short growing season. There isn’t enough warmth for trees to grow nor vegetation to decompose fully – so two metres of peat covers much of the upper dale.

Such unique conditions allow an assemblage of plants to thrive which are usually only found in Arctic or Alpine areas: ferns, mosses, liverworts and lichens, plus the famous Teesdale spring gentian (the sneezewort should be just as famous because generations of men found they could dry it, grind it and then sniff it like snuff).

Man followed the retreating ice sheets, hunting and gathering as he went. Then he noticed the potential of the minerals that outcropped here and there and tried to use them. On Holwick Fell, there are the remains of at least 50 medieval iron smelting sites, known as bloomeries, and of at least 500 pits that made charcoal that heated the bloomeries.

The fell, which we consider today to be pretty empty, was then a busy place of people mining, smelting, charcoal-making and tending their cattle.

The advent of Victorian technology made the dale more industrial, and Middleton-in-Teesdale grew up as the capital of the London Lead Mining Company.

There was even a pencil mill on the side of Cronkley Fell, the remains of which can still be seen today. It was in operation between 1847 and 1889, and it used waterpower to grind down some locally mined slate and then compress it so it could be used as pencils – or “widdies”, as the Teesdale dialect called them.

This is the fifth edition of a book which was first produced in 1965, with the chapters written by experts, many from Durham university.

They re-evaluate the history. It is a shock to read that Coldberry Gutter may not now be a hush. Coldberry Gutter is the great V in the daleside that can be seen from the High Force waterfall car park and it was thought that leadminers had built a reservoir above it which they had broken to create a torrent of water – a hush – which would wash away the rock to reveal the precious lead. Now, though, the experts say there was little hushing involved; this chasm is in fact a glacial meltwater channel.

Everything is affected by this broad sweep of history – even the birdlife. So we learn that the numbers of garden warblers and willow warblers are on the up, but the wood warbler and tree pipit have disappeared in the last five years. In the last 50 years, the corncrake and the dotterel have stopped breeding, whereas oystercatchers, goosanders, jackdaws and ringed plovers have begun breeding in recent years.

And the twite still clings on in upper Teesdale.

The book is available from the Durham Wildlife Trust at Rainton Meadows or the Low Barns Visitor Centre, Bowlees Visitor Centre, Middleton-in-Teesdale Tourist Information Centre and online from