Original: Merseyside is divided into two parts by the Mersey Estuary: the Metropolitan Borough of Wirral is located to the west of the estuary on the Wirral Peninsula; the rest of the county is located on the eastern side of the estuary.
Simplified: Merseyside is divided into two parts by the Mersey estuary: the Wirral is located on the west side of the estuary upon the Wirral Peninsula; the rest of the county is located on the east side.