erecting a memorial honoring Roosevelt. Congress authorized the memorial on May 21, 1932, but did not appropriate funds for the memorial for almost three decades. Frederick Law Olmsted Jr., a landscape architect known for his wildlife conservation efforts, as well as designs for the National Mall and other areas in the National Capital area (and whom President Theodore Roosevelt had appointed to the McMillan Commission back in 1901), developed a plan for the island. By 1935, the Civilian Conservation Corps had cleared much of the island and pulled down the house's remaining walls; today, only part of the mansion's foundation remains. Funds were finally designated by Congress in 1960. As with all historic areas administered by the National Park Service, the national memorial is listed on the National Register of Historic Places; the listing first appeared on October 15, 1966. The memorial was dedicated on October 27, 1967. Designed by Eric Gugler, the memorial includes a 17-foot (5 m) statue by sculptor Paul Manship, four large stone monoliths with some of Roosevelt's more famous quotations, and two large fountains. Geography and natural history The Potomac River surrounding the island is at sea level, part of the Chesapeake Bay estuary, with the river water fresh but tidal. A narrow channel, unofficially referred to as "Little River" by local users of the Potomac River, separates the island from the Virginia bank of the Potomac, with the main channel of the Potomac between the island and Georgetown, part of Washington, D.C. Surrounding scenery includes the Potomac Gorge and Key Bridge, Georgetown, Rosslyn, and the Kennedy Center. The Virginia state line follows the southern bank of the river, so, despite the fact that the primary access to the island is from Virginia, the island itself is entirely in the District of Columbia. The rocky western (upriver) and central portions of the island are part of the Piedmont Plateau, while the southeastern part is within the Atlantic Coastal Plain. At one point opposite Georgetown, the Atlantic Seaboard fall line between the Piedmont and the Coastal Plain can be seen as a natural phenomenon. The island has about of shoreline, and the highest area of the island (where the Mason mansion stood) is about above sea level. Spring floods coming down the Potomac from Appalachia inundate low-lying portions of island's shores regularly, usually several times each year, while much larger floods, often from the storm surges