Because one might have other minerals in it as well
Ridges, Ridges are elevated boundaries that divide watersheds
The building of the dam was proposed by Sun-Yat Sen, who is the father of modern China, to protect the river communities from floods.
Population density is a measurement of population per unit area, or exceptionally unit volume; it is a quantity of type number density. It is frequently applied to living organisms, most of the time to humans. It is a key geographical term. Hope this answered your question
