Those who have visited the Grand Canyon have typically seen layers of sediment in the gaping canyon, with different colors that mark the passage of time like the rings in a tree trunk.

(A) seen layers of sediment in the gaping canyon, with different colors that mark :

(B) seen layers of sediment in the gaping canyon, whose different colors mark
whose is used to modify people..

(C) been seeing layers of sediment in the gaping canyon, whose different colors are markers of
whose is used to modify people..

(D) been able to see layers of sediment in the gaping canyon, with different colors marking:

(E) seen layers of sediment in the gaping canyon, marking by different colors
Meaning issue..awkward or just pure plain crazy construction