A satellite in a polar orbit passes over both poles, but the earth rotates beneath it. The time taken for each orbit of the earth depends on the height of the satellite. If the satellite is in a circular orbit 260 kilometers above the surface it will have an orbital period of two hours.
The oldest layers are on the bottom thats why they are the oldest. Super position is what it is called if thats what your asking.
These are small eukaryotes
