Two-thirds of Wiltshire, a mostly rural county, lies on chalk, a kind of soft, white, porous limestone that is resistant to erosion, giving it a high chalk downland landscape. This chalk is part of a system of chalk downlands throughout eastern and southern England formed by the rocks of the Chalk Group and stretching from the Dorset Downs in the west to Dover in the east. The largest area of chalk in Wiltshire is Salisbury Plain, which is used mainly for arable agriculture and by the British Army as training ranges. The highest point in the county is the Tan Hill–Milk Hill ridge in the Pewsey Vale, just to the north of Salisbury Plain, at above sea level.
Two-thirds of Wiltshire, a mostly rural county, lies on chalk, a kind of soft, white, porous limestone that is resistant to erosion, giving it a high chalk downland landscape. This chalk is part of a system of chalk downlands throughout eastern and southern England formed by the rocks of the Chalk Group and stretching from the Dorset Downs in the west to Dover in the east. The largest area of chalk in Wiltshire is Salisbury Plain, which is used mainly for arable agriculture and by the British Army as training ranges. The highest point in the county is the Tan Hill–Milk Hill ridge in the Pewsey Vale, just to the north of Salisbury Plain, at above sea level.