Question: Which of the following describes the principle of original horizontality? Need Assignment Help? View Available Hint(s)for Part C Inclusions within a sedimentary rock are older than the sedimentary rock itself. Folded sedimentary layers were originally laid down flat and later deformed. The oldest sedimentary unit is located at the base of the sequence, while the youngest is at the top. A fault or dike that cut a sedimentary sequence is younger than the sedimentary rocks it breaks through. Undeformed sedimentary layers present on one side of a river-cut canyon are the same as those on the opposite side.