the park began in 1989. A $51 million campaign, announced in 1993, resulted in the restoration of bridle trails, the Mall, the Harlem Meer, and the North Woods, and the construction of the Dana Discovery Center on the Harlem Meer. This was followed by the Conservancy's overhaul of the near the Great Lawn and Turtle Pond, which was completed in 1997. The Upper Reservoir was decommissioned as a part of the city's water supply system in 1993, and was renamed after former U.S. first lady Jacqueline Kennedy Onassis the next year. During the mid-1990s, the Conservancy hired additional volunteers and implemented a zone-based system of management throughout the park. The Conservancy assumed much of the park's operations in early 1998. Renovations continued through the first decade of the 21st century, and a project to restore the pond was commenced in 2000. Four years later, the Conservancy replaced a chain-link fence with a replica of the original cast-iron fence that surrounded the Upper Reservoir. It started refurbishing the ceiling tiles of the Bethesda Arcade, which was completed in 2007. Soon after, the Central Park Conservancy began restoring the Ramble and Lake, in a project that was completed in 2012. Bank Rock Bridge was restored, and the Gill, which empties into the lake, was reconstructed to approximate its dramatic original form. The final feature to be restored was the East Meadow, which was rehabilitated in 2011. 2010s to present In 2014, the New York City Council proposed a study on the viability of banning vehicular traffic from the park's drives. The next year, mayor Bill de Blasio announced that West and East drives north of 72nd Street would be closed to vehicular traffic, because the city's data showed that closing the roads did not adversely impact traffic flows. Subsequently, in June 2018, the remaining drives south of 72nd Street were closed to vehicular traffic. Several structures were renovated. Belvedere Castle was closed in 2018 for an extensive renovation, reopening in June 2019. Later in 2018, it was announced that the Delacorte Theater would be closed from 2020 to 2022 for a $110 million rebuild. The Central Park Conservancy further announced that Lasker Rink would be closed for a $150 million renovation between 2021 and 2024. Landscape features Geology There are four different types of bedrock in Manhattan. In Central Park, Manhattan schist and Hartland schist, which are both metamorphosed sedimentary rock, are