Folkestone’s visible geology comprises three distinct layers of sedimentary rock.
The Lower Greensand formed under shallow seas about 120 million years ago. It was originally a sandy seabed and animal burrows can be seen fossilised in the rock. Ammonites, oysters, sea urchins and reptile fossils can also be found.
As the sea level rose about 112 million years ago, particles of silt formed a layer called the Gault Clay. Ammonites, crustaceans, fish and reptiles, along with microscopic animals called foraminifera inhabited the sea. Gault fossils are easily found on the beach at East Wear Bay.
Chalk began to form about 100 million years ago from the compacted remains of microscopic algae called coccoliths. A centimetre of chalk took about 250 years to form, but eventually created a layer over a kilometre thick. Fossilised ammonites, bivalves and sea urchins are common but fish and marine reptiles, including ichthyosaurs, can also be found.
Folkestone Warren and its rocks and fossils are world famous. For centuries collectors have visited the Warren and built up collections that are now found all over the world.
Collecting Natural History specimens such as fossils, rocks, butterflies, beetles or birds eggs, was a very popular hobby in Victorian and Edwardian times. Most collectors were amateur scientists and became experts in their particular fields, adding greatly to our knowledge of the flora and fauna around us.
Samuel Mackie was the first major collector of local fossils and geology. Much of his collection formed the first museum in Folkestone in 1858. Later, the museum purchased more fossils from the fossil dealer John Griffiths, who became a renowned expert on local fossils.
Many Folkestone collectors eventually donated their collections to the museum. To add to Mackie’s fossil collection, J.J. Giles, W.J. Austen and Ernest Joy donated significant butterfly and moth collections.
‘This Warren is a curious place. The soil here is composed of clay or gault, and numerous landslips have taken place…Children delight to roam here and play hide-and-seek, collect fossils, or pick
blackberries…it is a most suitable place for the children to paddle. No visitor should leave Folkestone without visiting the Warren.’
Notes on Folkestone by Arthur E. Larking 1899
‘Here we are, then, in the Warren. There is nothing quite like it in England. It is, indeed, one of
Nature’s storehouses, and crammed with good things. The very scenery is unique.’
Rambles around Folkestone by ‘Felix’, 1913
‘Oft have I scrambled o’er those white chalk-cliffs, or clambered homewards for six long miles o’er sea-weeded rocks with satchel loaded full of fossils gathered from the slippery shores of Eastwear Bay, where the dark-blue crumbling Gault daily yields its crop of glittering fossils to the destructive battering of the salt sea waves.’
Handbook of Folkestone by S. J. Mackie 1859