What does gravity mapping show?
the differences in population from place to place
the differences in mass from place to place
the differences in gravity between different planets
the differences in the magnetic force from place to place

not sure if this what   you'r looking for would be percent composition

for example, no new evidence will demonstrate that the earth does not orbit around the sun (heliocentric theory), or that living things are not made of cells (cell theory), that matter is not composed of atoms, or that the surface of the earth is not divided into solid plates that have moved over geological timescales .