Question

the earths layers are divided up by

Explanation:

The Earth's layers (crust, mantle, core) are divided by physical or chemical properties. Physically, they're separated by mechanical behavior (lithosphere, asthenosphere), and chemically by composition (crust, mantle, core). The key division is based on physical and chemical properties (or "composition and mechanical behavior").

Answer:

physical and chemical properties (or composition and mechanical behavior)