I recently rafted the San Juan river in Southern Utah, which flows into the Lake Powell reservoir. When the water levels in Lake Powell were very high, it extended far upstream into the San Juan River. This caused the river to stagnate and deposit enormous amounts of silt in the canyon.
When Lake Powell water level subsequently dropped, the river carved new meanders through the resulting silt beds, but within the much larger meanders that form the canyon. (Satellite Imagery from Google Maps)
The San Juan doesn't flash flood anymore due to the flow regulation of the upstream Navajo Dam, so it hasn't been able to wash out the silt.
Apparently "meanders in meanders" is not a unique phenomenon as Anders Sandberg has also captured it here, but I don't know where he took this picture.
Question: Can "meanders in meanders" also form naturally? How does this happen? Also, if there is a more scientific name for this phenomenon, it would be helpful.