Their entrypoint was in late-19th-century studies of the Sahara Desert.[34] سبخة sabkha, salt marsh. This Arabic word occurs occasionally in English and French in the 19th century. Sabkha with a technical meaning as coastal salt-flat terrain came into general use in sedimentology in the 20th century through numerous studies of the coastal salt flats on the eastern side of the Arabian peninsula.[35] وادي wādī, a river valley or gully.