The mere's were created by melting ice 10,000 years ago, the mere at Ellesmere is the largest of nine glacial meres in the area and some of the largest in England outside the Lake District. What makes them different from those in the Lake District is that they don't have a flow of water into them to maintain the level. In 1812 the Lady of Ellesmere House, took the unemployed people of the area and got them to work landscaping her garden. It was winter and all the soil from the gardens was wheelbarrowed across the frozen mere and left in a pile, when it thawed it settled into an artificial island. This was later named 'Moscow Island' and shortened to 'Cow Island'. The island is very popular with birdwatchers who visit to see the grey herons nesting.