The Sharon Plain is bounded by the Yarkon River in the south and the Nahal Tanninim (Crocodile River) on the north. It is 30 mi. [48 km.] from north to south and 10 mi. [16 km.] wide. Because of three parallel north–south kurkar (fossilized dune sandstone) ridges the wadis from the hill country of Manasseh have difficulty flowing into the Mediterranean Sea and thus in the Old Testament period, the plain was mainly swamp land.
During the Roman Period the swamps were drained and Herod the Great built, almost from scratch, the city of Caesarea.