Original: 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 and the rest of the county is located on the east 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.