Taygetus is transected by deep ravines through which tributaries flow into the Eurotas. At the foot of the massif is a zone of scree. To the east of that alluvial fans from Taygetus cover half the valley, making it asymmetrical. On that account it is often called the Evrotas Furrow. The Eurotas flows over a flood plain and also through a shallow aquifer of sand and gravel 10-60 m deep, graded with the deep end downstream. The gradient of the aquifer is a steep 1-3%. The highest hydraulic conductivity and transmissivity are near the junction of the Xerias and the Eurotas south of Sparti. To the east are older and finer sediments of alternating clay and marl beds, some of which are impermeable. Under the entire valley is a deep aquifer in the limestone floor, containing water permeating downward through the horsts. The Eurotas collects runoff and drains the deep aquifer on the east bank but loses water to the shallow aquifer on the west bank.