of the Fal is predominantly Devonian slates, shales and grits, with granite in the upper reaches. Land use is mainly agricultural with some woodland. Tributaries of the River Fal include the Truro River, River Kennal, Penryn River and Carnon River. Several tidal creeks discharge into the River Fal including Mylor Creek, Pill Creek, Penpol Creek, the Percuil River and Restronguet Creek. The Fal/Truro waterway is navigable between Falmouth and Truro. The River Fal is crossed by the King Harry Ferry, a vehicular chain ferry that links the villages of Feock and Philleigh approximately equidistant between Truro and Falmouth. The river flows through the Carrick Roads, a large ria that creates a natural harbour. Wildlife and conservation Five Sites of Special Scientific Interest (SSSI) have been designated along the River Fal. The river rises on Goss Moor which is both a National Nature Reserve and part of a SSSI. The wetland habitats and western dry heath communities were formed, since the Bronze Age, by the mining of the alluvial tin deposits. South Terras Mine SSSI is also a Geological Conservation Review (GCR) site of national importance and was once a commercial uranium mine. The Crowhill Valley SSSI between Grampound and St Stephen is an ancient woodland dominated by sessile oak on the slopes, and of willow and alder carr on the floodplain which has a rich ground flora. The species list includes many ancient woodland indicators including lichens such as Parmelia endochlora. The Upper Fal Estuary and Woods SSSI is mostly within the tidal area of the river between Tregony and Turnaware Point and includes mudflats, salt marsh and ancient woodland. The mudflats support nationally important numbers of black-tailed godwit as well as large populations of wintering waders and wildfowl such as curlew and golden plover. A series of transition zones occur from the salt marsh to scrub, where young trees attempt to grow despite the threat of the highest tides, to ancient woodland on the higher slopes. These zones and the estuary itself are important for otters. The lowest part of the Fal along with the Helford River is designated as the Fal and Helford Special Area of Conservation under the Habitats Directive for the shallow bays and inlets, sandbanks and mudflats, and for its salt marshes. Part of the area is also designated as an Important Plant Area and a SSSI (Lower Fal & Helford Intertidal) for the relatively