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Define relative dating techniques

These techniques were first articulated by Nicolas Steno, a Dane living in the Medici court of Italy in the 17th C.

There is an intimate coupling between the movement of the plates on the surface and the convection of the mantle (that is, the heat transfer caused by bulk movement of molecules within fluids).

Thus, oceanic plates and the adjoining mantle convection currents always move in the same direction — because the oceanic lithosphere is actually the rigid upper thermal boundary layer of the convecting mantle.

It can then be turned into a metamorphic rock by heat and pressure that change its mineral content, resulting in a characteristic fabric.

All three types may melt again, and when this happens, new magma is formed, from which an igneous rock may once more crystallize.

To study all three types of rock, geologists evaluate the minerals of which they are composed.

This coupling between rigid plates moving on the surface of the Earth and the convecting mantle is called plate tectonics.

Seismologists can use the arrival times of seismic waves in reverse to image the interior of the Earth.By combining these tools, geologists are able to chronicle the geological history of the Earth as a whole, and also to demonstrate the age of the Earth.Geology provides the primary evidence for plate tectonics, the evolutionary history of life, and the Earth's past climates.There are three major types of rock: igneous, sedimentary, and metamorphic.The rock cycle illustrates the relationships among them (see diagram).Long before geologists tried to quantify the age of the Earth they developed techniques to determine which geologic events preceded another, what are termed "relative age” relationships.