The image shows core samples of rock strata taken from three different regions on earth. all the fossils shown in the image are index fossils. identify the youngest layer and the oldest layer in the image. assume that no overturning took place.

Oldest layer - F3

Youngest layer - F2

Explanation:

The youngest Region  is region 1 and the oldest region is region 3. The fossils named F3 in the region 3 at the bottom is the oldest fossil. The fossil named F2 is the youngest layer.

It is given that no overturning happened. Thus, as we can see in region 1 Fossil f1 is at the base but the same fossil is at the second layer from top in region 2 and in region 3 there are more layers beneath this layer F1 and hence fossil named F3 is the oldest fossil among all.

a- all cells come from pre-existing cells