It lies in the midst of the flat fen country.
The south-eastern portion of the province consists of high fen resting on diluvial sand.
The word was derived in antiquity from the town of Helos in Laconia, but is more probably connected with 'Aos, a fen, or with the root of AEiv, to capture.
The western division consists of low fen or clay soil and presents a monotonous expanse of rich meadow-land, carefully drained in regular lines of canals bordered by stunted willows, and dotted over with windmills, the sails of canal craft and the clumps of elm and poplar which surround each isolated farm-house.
It lies on a gentle eminence in the flat fen country, and the fine Perpendicular tower and spire of the church of St Mary are a landmark from far.