Stream Capture

At the center of this map, Seventyfive Mile Canyon, on the left, is about to capture Tanner Canyon, on the right

At the center of this map, Seventyfive Mile Canyon, on the left, is about to capture Tanner Canyon, on the right

Because water rushing down the steep slopes at the upper ends of the canyons has far more erosive power than the gentler flows in the lower canyons, erosion proceeds rapidly headward into the surrounding plateau. If the headward-eroding canyon rim encounters another, lower-gradient stream that can't deepen its bed as rapidly, it will capture and divert the headwaters of the lower-gradient stream, further increasing the runoff and erosion in the steeper canyon.

If the headward-eroding canyon rim encounters another, lower-gradient stream that can't deepen its bed as rapidly, it will capture and divert the headwaters of the lower-gradient stream, further increasing the runoff and erosion in the steeper canyon.

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