ROOSEVELT ISLAND

island of Antarctica, in the northeastern part of the Ross Ice Shelf, Ross Dependency (New Zealand), south of the Bay of Whales, off the coast of Edward VII Land. The ice-covered island, 90 miles (145 km) long and 35 miles (56 km) wide, was discovered in 1934 by American explorer Richard Evelyn Byrd. Its mean absolute elevation exceeds 1,640 feet (500 m), and its ice varies from 1,300 to 2,950 feet (400 to 900 m) thick. Pioneering studies of ice-sheet seismology, made on Byrd's second Antarctic expedition (193335), showed that a large northwestern section of the shelf (Roosevelt Island) is actually grounded, i.e., not afloat. island in the East River, between the boroughs of Manhattan and Queens, New York City. Administratively part of Manhattan, it is 1.5 miles (about 2.5 km) long and 1/8 mile wide, with an area of 139 acres (56 hectares). In 1637 the Dutch governor Wouter van Twiller bought the island from the Indians, who called it Minnahanonck. In 1828 the city acquired it and built a workhouse and penitentiary, which became notorious. Formerly known as Blackwell's Island, it was renamed Welfare Island in 1921, and in 1973 its name was again changed to honour President Franklin D. Roosevelt. In 1934 the old institutions were replaced by city hospitals. In the 1970s the island was connected to Manhattan by an aerial tramway system, and moderate-income housing and shopping complexes were constructed there. A bridge connects the island to Queens.