The 12th and 13th centuries saw much prosperity in Dorset and the population grew substantially as a result. In order to provide the extra food required, additional land was enclosed for farming during this time. The quarrying of Purbeck Marble, a limestone that can be polished, brought wealth into the county and provided employment for stonecutters and masons. Large amounts of the stone were used in the construction of Salisbury Cathedral. The trade continues today but has declined since the 15th century when alabaster from Derbyshire became popular.