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Big Bend National Park
The chasm-like passage of Rio Grande River through Santa Elena Canyon suggests that the river channel is antecedent to ridge (Sierra De Santa Elena). An antecedent stream is a stream passage that existed on an earlier landscape which was then raised. As erosion wears away the landscape surface, the river channel cuts downward through structures buried below the surfaces.

Terlingua Creek enters the Rio Grande from the valley to the right.
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