The Vegetation of Some Springs and Wet Flushes on Tarn Moor Near Orton, Westmorland

1. Tarn Moor is an upland area of undrained, common moorland in central Westmorland. It overlies limestone rock and contains numerous springs. 2. The upper parts of the moor are dominated by Calluna vulgaris, and the hollows contain deep peat and mires of many kinds. Along the sides of the valleys there is an interrupted belt of `wet flush' vegetation overlying a shallow peat or mineral soil. Many of the springs emerge in this zone. 3. Around the springs large tufaceous mounds dominated by Philonotis fontana are frequently built up. Below them, and elsewhere where the surface drainage is pronounced, there are areas with a low plant cover. These areas have a surface of stony clay, covered by trickles of water (pH 8), and support a characteristic vegetation. They are believed to be erosion surfaces. 4. The margins of the open surfaces, and isolated masses of uneroded drift upon them, support a rich calcicole association. 5. Where springs are absent the `flush zone' supports a closed calcicole association similar to that of the margins of the open areas. Regions with small springs or pronounced surface drainage may have small open areas, and appear intermediate. 6. The vegetation of these areas is of a type not previously described from Britain. None the less it is probably not infrequent in upland limestone districts.