It is the largest granite surface in England, the largest expanse of un-glaciated upland in Great Britain and the largest and highest upland in southern Britain. The highest points are Yes Tor, rising to 619 m/2,030 feet, and High Willhays, which climbs to 621 m/2,039 feet. The public is able to roam freely on unenclosed, open moorland with some 10 million visits being made each year. The soils are acidic, undisturbed by intensive agriculture and the moor is exposed to strong winds and high rainfall. There are areas of blanket bog, heath, grassland, valley woodlands and some enclosed farmland. All these factors make Dartmoor a haven for the walker and wildlife.