Who introduced the concept of a downward limit to stream erosion?

The concept of a downward limit to stream erosion was introduced by John Wesley Powell. He recognized that streams and rivers have an ultimate base level, which can be understood as the lowest point to which they can erode. This base level is typically associated with the level of the body of water into which the stream flows, such as a river ending in an ocean, lake, or another river. Powell's contributions laid the groundwork for understanding how erosion is influenced by geological and hydrological factors and the dynamic nature of river systems in shaping the landscape.

Powell's ideas have been fundamental in geomorphology and hydrology, highlighting the interplay between geological processes and water flow. His work demonstrates how streams can only erode land down to a specific level, which in turn influences sediment transport and deposition. This concept is crucial for understanding river dynamics, landscape evolution, and ecological systems associated with aquatic environments.