In sedimentary rock the oldest fossils would be expected to be found in the bottom layer of rock .
In sedimentary rock, the oldest fossils would be expected to be found in the bottom layer of rock. This is based on the principle of superposition which states that in a sequence of strata that is laid down undisturbed, the older layer of rock will be at the bottom of the sequence, while the youngest layer will be at the top. For the bottom layer of a rock to be older, then the oldest fossils would be expected to be found in the bottom layer of sedimentary rocks.