Unlike the moors of the north-eastern parts of Yorkshire, the fells are not prolific in heather. It is possible to pass through Wensleydale--or, indeed, most of the dales--without seeing any heather at all. On the broad plateaux between the dales there are stretches of moor partially covered with ling; but in most instances the fells and moors are grown over at their higher levels with bent and coarse grass, generally of a browny-ochrish colour, broken here and there by an outcrop of limestone that shows gray against the swarthy vegetation. In the upper portions of the dales--even in the narrow river-side pastures--the fences are of stone, turned a very dark colour by exposure, and everywhere on the slopes of the hills a wide network of these enclosures can be seen traversing even the most precipitous ascents. Where the dales widen out towards the fat plains of the Vale of York, quickset hedges intermingle with the gaunt stone, and as one gets further eastwards the green hedge becomes triumphant. The stiles that are the fashion in the stone-fence districts make quite an interesting study to strangers, for, wood being an expensive luxury, and stone being extremely cheap, everything is formed of the more enduring material. Instead of a trap-gate, one generally finds an excessively narrow opening in the fences, only just giving space for the thickness of the average knee, and thus preventing the passage of the smallest lamb. Some stiles are constructed with a large flat stone projecting from each side, one slightly in front and overlapping the other, so that one can only pass through by making a very careful S-shaped movement. More common are the projecting stones, making a flight of precarious steps on each side of the wall.