The three populations that were chosen for further analysis are geographically distance from one another. Why does this approach make more sense than choosing three populations that are geographically close to one another?

this age may represent the age of the earth's accretion, of core formation, or of the material from which the earth formed. this dating is based on evidence from radiometric age-dating of meteorite material and is consistent with the radiometric ages of the oldest-known terrestrial and lunar samples.

which fault and or fold did you find most difficult to diagram