user: Question: What is the surface of the mountain range that contains the Elk Garden Mountain?
Columns: ['Mountain', 'Elevation', 'Range', 'State(s)', 'Surface']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Richland Balsam', '6,410 ft/1,950 m', 'Great Balsam Mtns.', 'N.C.', 'Grassy']
SQL:

assistant: SELECT "Surface" FROM "Table" WHERE "Mountain" = 'Elk Garden';