Friday, 10 June 2016

The Geology of Thurstaston Shore

On Saturday 21st May around eighty people came to Thurstaston for a guided geology walk presented by Hilary Davies of Liverpool Geological Society.

She provided a fascinating overview of the impact of glaciation on the Dee and Mersey Estuaries and explained how the ice sheets, when coming south, had been diverted eastward by the Welsh Mountains and had carved deep valleys as they moved inland. Apart from the visible sandstone outcrops in Wirral such as Thurstaston Hill the rest of the Peninsular is covered by glacial deposits of boulder clay – now called till. It is impermeable and so enables water courses to exist, such as the Arrowe Brook, Birkett, Dibbinsdale Brook and Fender.

We next walked along the beach and collected specimens of rock which were given to Hilary for comment. She detailed their individual geological age and history as igneous, metamorphic or sedimentary and told us of the locations from which the glacier had collected them, some from N.W. Scotland. Some samples demonstrated striation in which they had been scraped along rock whilst being gripped in the ice. Others showed where rock had been stressed and fractured allowing other quartz and minerals to enter in water and later to solidify. Even the rock armour forming the new sea defences below Dee Sailing Club revealed remarkable minerals and fossils and gave insight into the geology of North Wales from whence they had come.

We were treated to an inspirational presentation delivered with great clarity and detailed explanations and all in fine weather.

Stephen Ross

1 comment:

  1. Today, I went to the beach front with my kids. I found a sea shell
    and gave it to my 4 year old daughter and said "You can hear the ocean if you put this to your ear." She placed the shell to her ear and screamed.
    There was a hermit crab inside and it pinched her ear.

    She never wants to go back! LoL I know this is entirely off topic but I had to
    tell someone!