A conservation organization purchased 7,100 acres of timberland on the Mendocino County coast and immediately gave 2,900 acres to the state to nearly double the size of Sinkyone Wilderness State Park. The Trust for Public Land announced in San Francisco that it bought the rugged land on the Lost Coast from Georgia-Pacific Corp. for an undisclosed price. The park addition includes a seven-mile-long ocean-side strip of pristine black sand beaches, soaring cliffs, redwood forests and fern-fringed streams. The trust said it had reserved 3,800 acres inland from the new parklands for development of a timber management plan and the eventual sale for commercial forest production. The Save the Redwoods League will own 400 of the 7,100 acres that in time will be added to the state park.