South Gare is entirely man made, it was constructed between 1866 – 1888, its 2.5 miles long and contains an estimated 5 million tons of slag from the local blast furnaces, which shows the vast size of the industry in that period.
This particular area contains some intact balls that havent been attacked by the sea or covered by sand and vegetation.
If the intention was to create a form of sea defence, then using a by-product from the local industry was very enterprising for the time.