The river then flows southward through a steep gorge known as the Kali Gandaki Gorge, or Andha Galchi, between the mountains Dhaulagiri, elevation to the west and Annapurna I, elevation to the east. If one measures the depth of a canyon by the difference between the river height and the heights of the highest peaks on either side, this gorge is the world's deepest. The portion of the river directly between Dhaulagiri and Annapurna I, downstream from Tukuche), is at an elevation of , which is lower than Annapurna I. The river is older than the Himalayas. As tectonic activity forces the mountains higher, the river has cut through the uplift.