The southern branch (branche méridionale) originates between the faces of the Ailefroide and Pic Coolidge, below the Col de Coste Rouge ( m) and the Col de la Temple ( m). The steep north faces of the Ailefroide, Pic du Coup de Sabre and Pic Sans Nom tower 1,000 to 1,500 metres above the glacier. The arête, which runs over these peaks eastwards to Mont Pelvoux, is also called the Grand Muraille du Glacier Noir. Five summits along this crest (Ailefroide Central, Pointe Fourastier, Pic Sans Nom, Pointe Puiseux and Pointe Durand) exceed the 3,900 metre mark. On its left-hand side, the southern branch of the glacier is bounded by the eastern foothills of Pic Coolidge. Hemmed in between these two faces, the firn stream flows initially northeastwards before swinging north just before the two ice streams merge. Rubble first appears on the surface of the southern glacial branch in large quantities in its lower reaches.