Friday, 21 September 2012

Rocks and Birds

We were taken back in time - geological time - on our recent guided walk on Thurstaston beach.

The sandstone that is exposed in higher areas further inland on the Wirral is here 70 feet below the sand. The rock was formed over 200 million years ago at a latitude of 30 degrees in a desert-like climate. It gradually moved to its present location through the process of continental drift.

More recently, 13,000 years ago, the Irish Sea glacier travelled down from Scotland and through the Lake District until it encountered the Snowdonia glacier. The glaciers acted like bulldozers, scraping up a mixture of sand, clay and stones and when the ice melted these were left as the till (or boulder clay) cliffs on what is now the beach.

Hilary Davies, our geologist guide, identified stones from Scotland and the Lake District that had been washed out of the unstable cliffs. Ranger Lynne Greenstreet helped us identify the shelduck and other birds on the estuary mud as we completed a fascinating circular walk.

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