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Why can plateaus formed by crustal shortening be described as mountain ranges buried in their own debris?

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plateau The Columbia Plateau is uniformly covered with basaltic lava flows and spans an area of about 100,000 square miles in Idaho, Washington, and Oregon.

Plateaus formed by crustal shortening are described as mountain ranges buried in their own debris because of the specific way they evolve through internal drainage and sedimentation.1

In these regions, tectonic processes create high mountains along the plateau margins, which are then subjected to erosion. Unlike typical mountain ranges where rivers transport eroded material away to distant plains, these plateaus feature internal drainage systems. Consequently, the eroded debris—such as sediment and rock fragments—is trapped and deposited within the valleys and basins located between the mountains.1

Over time, these deposits fill the low-lying areas, creating broad, flat surfaces that contrast with the surrounding rugged, deformed mountain peaks. Because the original mountainous topography is progressively obscured by this accumulation of sediment, the resulting landform effectively functions as a mountain range that has been "buried" by its own erosional products. These features are most likely to survive in dry climates where the rate of erosion is slow enough to maintain the plateau's structure.1