unitary authority, geographic and historic county of Berkshire, England. The unitary authority extends westward from the district of Reading along both sides of the River Kennet and edges into the Berkshire Downs on the north and the Hampshire Downs on the south; both downs are composed of chalk and rise to elevations of between 600 to 800 feet (185 to 245 metres). The downs have occasional clumps of beech, and cereal grains (especially barley) are grown there. The Kennet River valley itself is devoted to pastureland upon which dairy cattle and the locally bred Berkshire pig (see photograph-->) are commonplace. The unitary authority, which comprises the southwestern third of the historic county of Berkshire, covers a large, mainly rural area centred on the town of Newbury. Area 272 square miles (704 square km). Pop. (2005 est.) 146,300.