Fig. 1: Large-scale geomorphology of Chomolungma.

a, A photograph of Chomolungma taken from its northern side. At this ___location, the Arun River flows towards the north away from Chomolungma before turning south through the Arun Gorge. b, Mountain peaks above 7,500 m in the Himalaya ranked by elevation. Chomolungma is off the almost linear relationship between rank and elevation. This relationship can be approximated with peaks drawn from a uniform distribution of elevations between 7,500 m and 8,400 m (blue curve) with an additional 300 m of uplift affecting 30% of these peaks, including the highest point (red curve). c, The enigmatic drainage network of the Kosi River. Local relief is highest where the gorge cuts through the Himalaya and elevation varies from 8,481 m to 1,140 m over a distance of only 35 km. The main faults of the Himalaya are the Main Frontal Thrust (MFT), the Main Boundary Thrust (MBT), the Main Central Thrust (MCT) and the South Tibetan Detachment System (STDS). The zone of high rock uplift rates is associated with the development of a mid-crustal duplex and is resolved with thermochronometry⁶. The rock uplift rate in this zone is set to 4 mm yr⁻¹ and is 0.5 mm yr⁻¹ to the south and 1 mm yr⁻¹ to the north. d, The χ map for the Kosi River catchment. e, Most of the divides between the catchments of tributaries and across the Himalayan divide are relatively stable. f, In contrast, in the Arun River and the tributaries to the east and west, χ varies considerably.