|The saving and wise use of natural resources is ____.
|A mineral's ability to split easily along flat surfaces is ____.
|The water on, under, and over Earth's the surface is its ____.
|The hardest naturally-occurring mineral on Earth is ____.
|The rigid lithosphere floats atop the slowly flowing ____.
|The removal of sediments by wind or water is called ____.
|The ____ has igneous, metamorphic, and sedimentary rocks.
|The Earth's ____ is composed of hot liquid iron and nickel.