This is a photograph of the Painted Desert in Arizona. These layers of rock have not been folded or overturned, so we know that the layer on the bottom is the oldest. This is based on:

1. The Law of Superposition

   Yes! The Law of Superposition tells us that unless the layers have been disturbed, they will be in order of their age, with the youngest on the top, and the oldest on the bottom.

2. The Law of Crosscutting

   No. The Law of Crosscutting tells us that a feature (crack, fault, igneous intrusion, etc.) that cuts through a layer of rock is younger than the layer it cuts through. That makes sense, because the layer would have to be there first, before it could be broken by a fault, etc.

3. The Law of Relativity

   No. There is a theory of relativity, which deals with the basics of physics, not geology. There is no Law of Relativity.

4. The Law of Thermodynamics

   No. The Law of Thermodynamics deals with energy, not with layers of rock.

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