Marley Fen | Wytham WoodsMarley Fen is a peat-based calcareous or alkaline hillside spring-fed fen which has probably been there for over 10,000 years. Fens are rare species-rich habitats and only about 25,000 ha of lowland fen remains in England. Alkaline fens will only develop https://www.wythamwoods.ox.ac.uk/marley-fen