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Why are continents less likely than oceanic crust to be subducted into the mantle?

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continental landform Davis's proposed landscape-development states. The morphology shown is not actually time-indicative. For example, A could be a gully system in soft sediment or a canyon such as the Royal Gorge in Colorado, which is millions of years old. The ridge-ravine topography of B would normally develop under humid conditions, but the river meandering on alluvium indicates a prior or extraneous non-humid aggrading mechanism. The riverine plain of C implies a complex history of planation and aggradation in a current fluvial mode.

Continents are less likely than oceanic crust to be subducted into the mantle primarily due to their lower density and greater buoyancy.12

While oceanic crust is composed of basaltic rock with a density of approximately 2.9 to 3 grams per cubic centimeter, continental crust is broadly granitic and less dense, at about 2.7 grams per cubic centimeter. This density difference causes continental crust to float higher in the mantle, effectively preventing it from sinking during plate convergence.12

Because of this buoyancy, when a continental plate and an oceanic plate meet at a subduction zone, the denser oceanic plate is preferentially forced downward into the mantle. This process ensures that continents are preserved over geologic time, which is why continental rocks can be billions of years old, whereas oceanic crust is continuously recycled and is generally much younger.23