The upper Yangtze changed course catastrophically at least twice. Abandoned channels filled with sediments that show when rivers jumped valleys.
Gisling, CC BY-SA 3.0, via Wikimedia Commons
A river's ancient detours
The Jinshajiang, or "Gold Sand River," is the name for the upper section of the Yangtze River. In the mountainous terrain of Yunnan province, this powerful river has not always followed its present-day channel. Geological evidence shows the river has dramatically changed its path in a process called avulsion, where a river abruptly abandons its channel to flow along a new one. This part of China sits on the southeastern margin of the Tibetan Plateau, a region shaped by the ongoing collision of the Indian and Eurasian tectonic plates. This intense geological activity causes rapid uplift and faulting, led to large-scale landscape changes, including the rerouting of entire river systems.
Before establishing its modern course, the upper Yangtze did not flow eastward. Instead, a paleo-Jinshajiang River likely flowed south, joining other rivers and heading toward the Indochina block. Geologists have identified abandoned river channels and thick deposits of lake sediments that show these ancient avulsion events. These features show a landscape in flux, where rivers were captured and redirected by evolving topography.
The sedimentary record of a valley jump
Near the famous First Bend of the Yangtze, geological studies have uncovered the history of these dramatic shifts. One major event involved a landslide that blocked the river around 79,300 years ago. This natural dam created a large lake upstream in an area called the Yinduba paleolandslide-dammed lake. This lake existed for at least 20,000 years before the dam was breached and the river established a new path. Another landslide-damming event in the region occurred around 60,000 years ago, also forming a short-lived lake.
Scientists determine the age of these events by studying the layers of fine-grained sediment left behind by the ancient lakes. Using a technique called Optically Stimulated Luminescence (OSL) dating, they can measure the last time mineral grains, like quartz, were exposed to sunlight. When sediment is buried in a lakebed, it is shielded from light. The OSL method measures the amount of background radiation the quartz grains have absorbed since burial, effectively showing how long they have been hidden in darkness. These dates provide a precise timeline for when the river was forced from its old channel and began carving a new one, eventually creating dramatic features like the Tiger Leaping Gorge.
💡Fun Facts
The river's name, Jinshajiang, translates to "Gold Sand River" because of the gold dust historically panned from its waters.
The Tiger Leaping Gorge, carved by the river after one of its course changes, is one of the deepest river canyons in the world, with a maximum depth of about 3,790 meters (12,434 feet) from river to peak.
The tectonic uplift that causes these landscape changes is still active, with the Qinghai-Tibet Plateau continuing to rise.
Landslides frequently dam the Jinsha River even today; two successive landslides at Baige blocked the river in 2018, creating a large lake and subsequent flood.
This is a large, natural geological area and is always accessible. Specific parks like Tiger Leaping Gorge have defined hours, typically from early morning to late afternoon.
Admission
Access to the general region is free. Entry to designated scenic areas and parks, such as Tiger Leaping Gorge, requires an admission fee.
Accessibility
The terrain is mountainous and rugged. Hiking trails, like the famous one through Tiger Leaping Gorge, can be strenuous and steep. Main viewpoints are often accessible by road.
The Jinshajiang River Avulsion HistoryYunnan, China
