Which mountain does the river source Blue Nile located? State the height of the mountain.
SELECT T1.Name, T1.Height FROM mountain AS T1 INNER JOIN geo_mountain AS T2 ON T1.Name = T2.Mountain INNER JOIN province AS T3 ON T3.Name = T2.Province INNER JOIN geo_source AS T4 ON T4.Province = T3.Name WHERE T4.River = 'Blue Nile'