1. River Incision: During periods of high precipitation or increased runoff, rivers may experience increased flow and erosive power. This leads to the incision of the river channel into the underlying bedrock or sediments.
2. Aggradation: After a period of incision, the river's energy may decrease due to reduced flow or sediment supply. This allows sediments to be deposited within the river channel and on its banks, leading to the formation of an alluvial terrace.
3. Lateral Migration: As the river flows, it may meander and migrate laterally across its floodplain. This process results in the deposition of sediments on one side of the river while eroding the opposite bank. Over time, this lateral migration creates a series of terraces at different levels along the river valley.
4. Matching of Terraces: The terraces formed by the processes of incision and aggradation can become "matched" when they are located at corresponding elevations on opposite sides of the river valley. This matching occurs because the river's erosive and depositional processes tend to create terraces at similar heights.
5. Climatic and Tectonic Influences: The formation of matched alluvial terraces can also be influenced by climatic and tectonic factors. Changes in climate, such as variations in precipitation or sediment supply, can affect the river's erosional and depositional processes and lead to the formation of terraces. Additionally, tectonic uplift or subsidence can modify the river's gradient and influence the formation of terraces.
The resulting matched alluvial terraces are often found in pairs or groups, with each terrace representing a former floodplain of the river at different stages of its history. These terraces serve as important geomorphic features that provide insights into the past behavior and evolution of the river system and the surrounding landscape.
