Why are seismic waves useful for studying the struc- ture of Earth's interior?
A S waves cannot pass through liquids.
B S waves and P waves both travel through Earth's
interior.
C Seismic waves change direction when the density of
rock layers changes
D All of the above are reasons that seismic waves are
useful for studying the structure of Earth's interior.

a physical change is being made.

1. the geologists have established a set of principals that can can be used o determine the relative ages of rock. this principal is applied to sedimentary and volcanic rocks. the rocks exposed to wall of grand canyon has layers and by studying the number of horizontal layers in the rock(strata) the relative age can be determined. the layer first formed will appear at the bottom and the the layer of strata last formed appear at the top. by using this information the approximate age of rocks can be determined.

2. carbon dating is used to find the relative age of rock in numbers which means for the rocks that has age between 1-70,000 years.

3. for the rocks of age range between 1,000 - billion of years potassium-argon dating is used.