Although organic deposits are more limited than other types of topsoil, they occupy a significant part of the land surface and are important from an environmental and agricultural point of view. Organic deposits are most commonly formed in coastal marshes and terrestrial swamps. Where the water is shallow, characteristic flora species such as bogs, reeds and common grass are found. In Greece, reeds, rushes and willows grow in such areas, e.g. in the Prespes region. As these plant organisms die or shed their leaves, a layer of organic debris is formed on the bottom. Due to the presence of water, these organic residues do not oxidise and, over the years, they accumulate and form thick organic deposits. They are particularly suitable for growing rye, potatoes and grassland.