C289 Spiritualization

Looking ahead, he saw two precipitous cliffs slanted into the sky, with two cliffs standing between each other like a mountain that had been split open by a sharp axe. A crack appeared on the rock ceiling, and a ray of light from the sky seeped in, looking like a blue rainbow crossing the sky, looking like the work of a ghost.

Judging from the convexity of the two sides of the cliff