Final answer:
A high sediment deposition rate exceeding longshore current redistribution typically results in the formation of deltas, which are accumulation zones of sand and mud at river mouths entering still bodies like oceans or lakes.
Step-by-step explanation:
When the sediment deposition rate greatly exceeds the rate of sediment redistribution by the longshore current, new geological features are created. This discrepancy in sediment management typically leads to the formation of deltas, which are low-elevation areas of sand and mud at the mouth of rivers. Deltas form as a river deposits its sediment load into the ocean or a lake, and are facilitated when the body of water has minimal currents or wave action to redistribute the freshly deposited silt.
In the instance of a high sediment deposition rate not adequately balanced by longshore drift, the accumulation of sediment can generate large deltaic complexes. These structures are composed of layers of deposited sediment that may include sand, silt, and clay, along with organic material. The pattern of deposition may be observable in sediment cores, providing evidence of past environmental conditions and changes in sea level, as described by the principles such as Walther's Law.