<P> For the simplified model shown the new density is given by: ρ 1 = ρ c c h 1 + c (\ displaystyle \ rho _ (1) = \ rho _ (c) (\ frac (c) (h_ (1) + c))), where h 1 (\ displaystyle h_ (1)) is the height of the mountain and c the thickness of the crust . </P> <P> This hypothesis was suggested to explain how large topographic loads such as seamounts (e.g. Hawaiian Islands) could be compensated by regional rather than local displacement of the lithosphere . This is the more general solution for lithospheric flexure, as it approaches the locally compensated models above as the load becomes much larger than a flexural wavelength or the flexural rigidity of the lithosphere approaches zero . </P> <P> When large amounts of sediment are deposited on a particular region, the immense weight of the new sediment may cause the crust below to sink . Similarly, when large amounts of material are eroded away from a region, the land may rise to compensate . Therefore, as a mountain range is eroded, the (reduced) range rebounds upwards (to a certain extent) to be eroded further . Some of the rock strata now visible at the ground surface may have spent much of their history at great depths below the surface buried under other strata, to be eventually exposed as those other strata eroded away and the lower layers rebounded upwards . </P> <P> An analogy may be made with an iceberg--it always floats with a certain proportion of its mass below the surface of the water . If more ice is added to the top of the iceberg, the iceberg will sink lower in the water . If a layer of ice is somehow sliced off the top of the iceberg, the remaining iceberg will rise . Similarly, Earth's lithosphere "floats" in the asthenosphere . </P>

How is the concept of isostasy related to mountain building