Yosemite National Park is famous for towering waterfalls, giant sequoia trees and massive granite cliffs. But at an out-of-the-way spot near the park’s western boundary few visitors ever see, a landmark of a different type is taking shape. Workers are making progress this summer on an ambitious plan to turn a 400-acre property that was used for generations as a cattle pasture back into a healthy Sierra Nevada meadow. The project at Ackerson Meadow, the largest wetlands restoration in Yosemite’s history, involves filling in massive amounts of erosion — including a 3-mile long gully that is 14 feet deep and 100 feet wide — with hundreds of truckloads of dirt and mulch, along with planting 425,000 native plants and more than 700 pounds of wildflower seeds.