Friday, 26 August 2016

An amazing bit of limestone pavement...by Fergus McTaggart

Hutton Roof Crags
In the same year that the British Geological Survey was founded (1835), Henry Fox Talbot produced the first silver chloride camera negatives on paper and conceived the two-step negative-positive procedure for making photos that traditional cameras still use today. Since those early days of photography, it has grown to become the geologist’s faithful companion. Photography has been crucial in gathering a scientific evidence base that paints an ever more detailed picture of how our planet works.  

For World Photo Day last Friday, we did a straw poll of our favourite British Geological Survey image. Hutton Roof Crags, which lies between the Lake District and the Yorkshire Dales national parks, came out on top. This part of Northern England is underlain by an amazing array of different rock types, with an exposed geological history spanning almost 500 million years. Over the last 200 years, its mineral wealth has been crucial for industrial change and has contributed to the wealth of the UK. 

Our rich and complex geology has also created some of our most dramatic landscapes: providing geologists with major clues as to how our planet formed and evolved. It is indeed no coincidence that many UK geologists, including some that worked with and for the British Geological Survey are regarded as the pioneers of geology

Hutton Roof Crags, at Holme Park Fell in Cumbria, is made of limestone that formed during the Carboniferous period over 300 million years ago. Due to the solubility of limestone, natural weathering often results in the formation of limestone pavement. This strange-looking landscape is made up of limestone blocks that developed in between a network of natural vertical fissures that formed as cracks or fractures within the limestone were widened and deepened by acidic water. 

The lack of soil coverage means that very little, if any vegetation can grow on top of the limestone. However, the presence of deep fissures or ‘grikes’ allows for soil development, and provides shade, humidity and protection from grazing. Because of these unique conditions, limestone pavement can host typical woodland species, not normally associated with apparently exposed and barren landscapes. 

Read more about how the complex geology of the UK has helped us to understand our planet at Discovering Geology

Fergus McTaggart is Head of Photography at the British Geological Survey



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