The Andean Plateau in Peru reaches about 3.7 kilometers in elevation. Canyons that cut into it are 2–3 kilometers deep. For comparison, the Grand Canyon is less than 2 kilometers deep at its deepest point.
Scientists tested two main ideas for how the canyons formed: sudden uplift from earthquakes and long periods of heavy rainfall. A research team used computer models that combined the region's tectonic history with recent estimates of climate and precipitation.
The models showed that neither uplift nor rainfall alone explained the deep valleys. Instead, river capture — when one river erodes across a ridge and diverts a neighboring river — gave the capturing river extra water and power to cut much deeper. Slower uplift then let rivers cut through ridgelines.
Difficult words
- elevation — height above sea level or ground
- canyon — a deep valley with steep sidesCanyons
- uplift — the rising of land over long time
- precipitation — water that falls from the sky
- river capture — when one river diverts another by erosion
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Discussion questions
- Which explanation (uplift, rainfall, or river capture) seems most believable to you? Why?
- Have you ever visited a high plateau or a deep canyon? Describe it.
- Do you think computer models can help scientists understand landscapes? Why or why not?
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