Simplify the following text for a Grade 7 native English-speaking person.
Original: Salisbury Plain is a chalk plateau in central southern England covering 300 s. It is part of the Southern England Chalk Formation and largely lies within the county of Wiltshire , with a little in Hampshire .
Simplified: Salisbury Plain is a chalk plateau in central southern England covering 300 s. It largely lies within the county of Wiltshire , with a little in Hampshire .