Near the coast, halfway between the Quantocks and the Mendips, and lying parallel to them, is the low ridge of the Polden Hills. On either side is a coastal plain and wetlands area known as the Somerset Levels, an area of about , much of which is about above sea level. The northeasterly part of the Levels is drained by the Axe and Brue, and the southwesterly part by the Parrett and its main tributary, the Tone. This part of the Levels has traditionally been known as Sedgemoor, and to the east is Glastonbury Tor, an isolated hill projecting from the low-lying plain.