The principle of ________ describes the balance of forces between internal pressures in the lithosphere and mantle. It allows for the less dense continental material to float on the denser mantle.

Of iso, same; stasy, state; word derived from the Greek; its meaning speaks of the equilibrium state of the portions of the earth's crust and how they are permanently compensated. It is not a static equilibrium but a dynamic one, its behavior implies the recognition of erosion and sedimentation phenomena as exogenous factors and the rearrangement of cortical blocks as endogenous factors.

The earth's crust, having a lower density than the underlying layer (outer mantle), will submerge in it and float, in a measure proportional to the height, that is to say that the mountains will have deeper roots than the plains, the lowlands or the bottoms sailors

The theory has been widely known in some cases as "Plate Tectonics" and in others as "Continental Drift". Today, the first title conforms more to the scientific truth since the continents travel as passengers on the tectonic plates whose areal dimension is much greater.