Final answer:
Silt and sand are deposited in locations where river currents slow down, typically at the meeting point with larger bodies of water like oceans or large lakes, forming deltas or estuaries. Deltas form in areas with low ocean current activity, while estuaries occur where wave action is stronger.
Step-by-step explanation:
The site where sand and silt are deposited by the slowing of the current is typically found where a river reaches a larger body of water, such as an ocean or a large lake. When the water flow slows down, the sediment the river has carried, including sand and silt, begins to settle. This process occurs because the energy of the river diminishes, reducing its capacity to carry these particles. An example of such a geological feature is a delta, which often takes a triangular shape as the river splits into multiple channels, depositing sediments and forming low-elevation areas.A specific environment where this occurs is where rivers with high silt content meet oceans with minimal wave action, resulting in the buildup of deltas. Conversely, in areas with strong ocean currents or waves, the deposition can lead to the formation of estuaries, where freshwater and seawater mix and sediments are sorted differently. Close to the shore, sand is primarily deposited, while silt and clay settle further away. The boundary between these deposits is often gradational, leading to a smooth transition from one sediment type to another.
The phenomenon of deposition also leads to other features like load casts, where heavier sediment, such as sand, is deposited on top of lighter, water-saturated sediments, like silt or clay, creating impressions in the layers beneath.