Complex sentence: Climbers Wilfrid Noyce and A. D. M. Cox climbed to within of the summit via the north ridge; to an approximate altitude of 22,793 ft., but did not complete the ascent; they had promised not to set foot on the actual summit.
Split into simpler sentences: Climbers Wilfrid Noyce and A. D. M. Cox climbed to within of the summit via the north ridge, to an approximate altitude of. They did not complete the ascent, as they had promised not to set foot on the actual summit.