谷 and 峠: a valley and a mountain pass
Compare a road along a valley with one crossing a pass, separating a summit visible from a pass from the viewer’s position.
Low ground between mountains
谷, read たに, means a valley between mountains. 谷に沿って道が続いています。 says that a road continues along the valley.
谷を見下ろしました。 says that someone looked down at the valley. It does not state that the viewer descended to its floor.
A pass on a route over the mountains
峠, read とうげ, means a mountain pass. 峠を越えると、別の村があります。 says that another village lies beyond the pass.
峠で少し休みました。 says that someone rested briefly at the pass. で marks the rest location without establishing arrival at the village.
A pass and a summit are different references
峠から山の頂上が見えました。 says that the mountain’s summit was visible from the pass. 峠 is the viewing position, and 頂上 is the visible object.
谷を通る道 is a road through the valley, while 峠を越える道 is a road crossing the pass. Do not translate both landforms as a mountain summit.
Does 峠から山の頂上が見えました。 place the viewer on the mountain’s summit?
Show the answer and why
No. The viewing position is the pass, and the summit is what was visible from there.