CREATE TABLE table_name_77 (elevation__ft_ INT, isolation VARCHAR, range VARCHAR, peak_name VARCHAR)

WHAT IS THE ELEVATION OF THE UNAKA MOUNTAINS, IN ROAN HIGH BLUFF PEAK, AND ISOLATION LARGER THAN 1.54?
SELECT AVG(elevation__ft_) FROM table_name_77 WHERE range = "unaka mountains" AND peak_name = "roan high bluff" AND isolation > 1.54
SELECT AVG("elevation__ft_") FROM "table_name_77" WHERE "isolation" > 1.54 AND "peak_name" = "roan high bluff" AND "range" = "unaka mountains"