Underneath the surface of Upper Weardale
Exploring what lies beneath the surface of our landscape, this chapter has been written by Brian Young, Honorary Research Fellow, Department of Earth Sciences, University of Durham, and retired British Geological Survey District Geologist for Northern England.
Buried beneath the Dale, but reached by deep boreholes, are rocks dating from around 450 million years ago formed when the area that was to become Northern England lay far south of the equator. These include slates that originated as mud on the floor of a deep ocean, and volcanic rocks and granite formed as the earth's tectonic plates collided and destroyed an ancient ocean.
Over the millions of years since the layers have produced rocks visible today which have been critical in shaping the physical, industrial and social character, and even the style of buildings across the Dale.
Many of the deposits beneath the surface are distinctive, such as Frosterley Marble; not a true marble, but a black limestone crowded with striking white fossils of the coral Dibunophyllum, long valued as an ornamental stone, with fine examples to be seen in local churches and in Durham Cathedral.
Mineral deposits, formed as mineral-rich ground waters cooled include ores such as lead, iron and zinc. There are even larger amounts of 'spar' minerals, dominated by quartz, calcite, ankerite and fluorite, many of which have formed as spectacularly beautiful crystals.
Weardale is internationally famous as the source of some of the world's finest examples of fluorite, to be seen in museums across the world.
There is plenty more in the chapter, available to download from the website. If you would like to purchase the book that provides a complete perspective on the Natural History of Upper Weardale, perhaps with the complimentary Natural History of Upper Teesdale, these are available online from Durham Wildlife Trust.
More chapters will be uploaded to Living Uplands over the coming weeks. Stay tuned.