The first thing for the 1998 expedition team to do was how to define the entrance of the great canyon scientifically. The entrance of canyon is at the foot of Mount Namjagbarwa.

The Entrance to the Great Canyon

　　The northwestern side of Nyedeng is a part where the Yarlung Zangbo River will bend and enter the Canyon. Four ancient castle relics stand on the riverbank. The scientists believed they are very good symbolic buildings. Observing from the steep cliffs in the highest point of the ancient castle relics, people can see great mountains in the east; there is a shortcut zigzagged in the middle of the mountain. The west bank of the river is the Yarlung Zangbo Canyon. It's really a pass one can hold against ten thousand! Standing on the high and steep riverbank, one can have a wide field of vision. Looking at the west, one can see the Yarlung Zangbo River flowing slowly from the west to the east until it reaches under his feet; then it turns to the north abruptly. At the place when it turns, there are some topographical terrains formed by sands and they can really make people gaping. The river valley turns narrow immediately after it bends; the river course shrinks in-between the base rock mountain mouth in the left bank and the fan-shaped till ground. The water current becomes more rapid and rolls on towards the north in mountainous waves. There is a piece of sand land on the left bank of the river. After the currents in the south-north direction roll on for about 400-500 meters along the steep cliffs where the castles locate, the river valley suddenly turns towards the east. This is a magnificent scene in the entrance of the Great Yarlung Zangbo Canyon. We are deeply attracted by it. Experts of different subjects reached an agreement after careful observation on site; they unanimously agreed that the riverbank base rock beside the 4^th castle relic is the geological coordinate point for the entrance of the great canyon. 

"Monument for the first Human Beings' Hiking Through the Great Canyon" set up (by Du Zequan)

　　The scientific expedition team named the surveying benchmark at the entrance of the great canyon as Kexin No. 1. This is a great result achieved by the scientific expedition team in the first day of their field expedition. Kexin means it is a result achieved through the cooperation of scientists and workers in the news front. Thereafter, the first surveying benchmark was established in the great canyon district. The geological coordinate of the entrance of the great canyon is beside the ancient castle of Datogka village, Mainling County. Its longitude and latitude coordinates are separately 94°54'20" E and 29°32'36" N; its elevation is 3108; and the flowing volume into the canyon is 2000 cubic meters per second. Afterwards, the scientific expedition team established Kexin No. 2 and Kexin No. 3 benchmarks separately on the Jifang Bridge in Medog county and the monument established for mankind to hike through the great canyon for the first time in Zhaqu. The three surveying benchmarks provided a lot of valuable surveying results for surveying science and geodynamics (about crustal movement) research in the great canyon district.