Misfit stream

A misfit stream is a river that is either too large or too small to have eroded the valley or cave passage in which it flows.

[1][2] An underfit stream can result when glaciation modifies the landscape by creating glacial troughs.

If misfit streams are widespread in an area, climate change, particularly a reduction in precipitation, is likely to be the cause.

[2] If a single river appears to be a misfit stream, it may be as a result of human activity through groundwater extraction or dam construction upstream.

For instance, New Zealand's largest river (the Waikato) used to flow through the Hauraki Plains to the North Island's east coast, but changed its course to exit on the west coast due to a large volcanic eruption, leaving its former course through the 1-km wide Hinuera Gap occupied by only a small stream.