The principle of fossil succession states that different types of fossil organisms are younger in the deepest layers of rock generally leave behind hard parts occur most often in sedimentary rock succeed one another in a definite order

a mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics. this uplifting of the ocean floor occurs when convection currents rise in the mantle beneath the oceanic crust and create magma where two tectonic plates meet at a divergent boundary.a geomagnetic reversal is a change in a planet's magnetic field such that the positions of magnetic north and magnetic south are interchanged.