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Why does thermal expansion of rocks raise the land surface?

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A car drives along the Trans-Canada Highway with Mount Sir Donald's sharp, snow-capped peak rising above forested slopes in the Selkirk Mountains, British Columbia. — mountain Mount Sir Donald in the Selkirk Mountains, British Columbia, looms above a segment of the Trans-Canada Highway.

Like most materials, rocks undergo thermal expansion when they are heated. When the lithosphere or the upper mantle beneath a broad region is rapidly warmed—often due to the upwelling of hot material from the asthenosphere—the resulting increase in temperature causes the rock material to expand.123

This expansion of the outer 100 to 200 kilometres of the Earth increases the volume of the underlying crust and mantle, which physically pushes the surface upward. This process is a primary mechanism for creating high-elevation landforms, such as plateaus and mountain ranges, even in areas that lack volcanism or crustal shortening. Notable examples of landforms elevated significantly by this process include the Ethiopian Plateau and the Massif Central in France. Conversely, when this material cools, it undergoes thermal contraction, which can cause the land surface to subside.123