Final answer:
Isostasy refers to the recognition that the crust floats on the denser mantle. The crust is the outer layer of the Earth, while the mantle is the layer surrounding the core. Understanding isostasy is important in comprehending the Earth's structure.
Step-by-step explanation:
Isostasy refers to the recognition that the crust floats on the denser mantle. The Earth's interior consists of an inner and outer core, the mantle, and the crust. The crust is the thin outer layer of the Earth and can be either continental or oceanic. It varies in thickness, composition, and density. The mantle is less dense than the core and surrounds it. It can behave in a plastic manner, allowing it to flow slowly. Therefore, the recognition that the crust floats on the denser mantle is a key concept in understanding the Earth's structure.